Composite belt as well as preparation method and manufacturing equipment thereof

Abstract

The invention provides a composite belt and a preparation method and manufacturing equipment thereof. The lithium melt is conveyed to the die head through the melt conveying system under the protective atmosphere; the continuously conveyed base material is coated by the die head under the combined action of the protective gas and a stirring device in the die head; the composite belt with a continuous and uniform coating layer is successfully prepared through the further action of cooling shaping and a calendering mechanism; and the preparation of a plurality of coating layers can be simultaneously realized in the width direction of the base material. In addition, on the basis that continuity and uniformity are achieved, the minimum thickness of the composite belt can reach 0.1 micrometer. The first coulombic efficiency of the battery can be improved, the cycling stability of the battery is enhanced, and the service life of the battery is prolonged; and a more efficient and safer solution is provided for the preparation of the composite belt mainly comprising lithium and sodium in the battery.

Description

Technical Field

[0001] The invention belongs to the technical field of battery production, and in particular relates to a composite tape and a preparation method and manufacturing equipment thereof. Background Art

[0002] During the first charge and discharge process of lithium-ion batteries and sodium-ion batteries, the organic electrolyte will undergo reduction decomposition on the surface of the negative electrode such as graphite to form a solid electrolyte interface film (SEI). This process not only consumes a large amount of lithium, resulting in a low coulombic efficiency (ICE) of the first cycle, but also reduces the capacity, energy density and life of the battery. In order to deal with this problem, researchers and engineers have been looking for effective solutions.

[0003] Pre-lithiation is an effective method to improve the energy density of lithium-ion batteries. Pre-lithiation refers to the introduction of additional lithium sources into the positive or negative electrode materials of the battery by some means before the battery is assembled to compensate for the irreversible lithium loss in the first cycle.

[0004] The pre-lithiation method mainly includes spreading lithium powder on the surface of the substrate and rolling and compounding lithium foil or lithium metal composite tape with the substrate. However, there are some significant problems with the existing lithium powder and rolling composite schemes. When using lithium powder for pre-lithiation, due to the extremely active chemical properties of metallic lithium and the large specific surface area of ​​the powdered material, the risk of combustion and explosion of lithium-ion batteries is significantly increased. In addition, the uneven distribution of lithium powder inside the battery can easily lead to local lithium excess, further increasing safety risks.

[0005] Although the method of using lithium foil or lithium metal composite tape for calendering and compounding can avoid the problem of lithium powder dispersion, it also has its own limitations. At present, the industrial production of commercial lithium foil is mainly achieved through extrusion, rolling and surface passivation. Thin metal lithium foil with a thickness of 20-100μm can be prepared by multi-roll rolling, but due to the high viscosity and poor mechanical processing performance of metallic lithium at room temperature, it is difficult to obtain a thinner thickness. After conventional lithium tapes are assembled into lithium batteries, the lithium layer may remain, posing a safety hazard. In addition, since the negative electrode sheet of lithium batteries is usually coated with a wide width, leaving a blank in the middle as a current collector, this requires the negative electrode sheet to be divided into multiple strips before calendering the lithium tape, and then calendering pre-lithiation. This process not only reduces production efficiency, but also cannot achieve uniform pre-lithiation due to the discontinuity of the lithium layer.

[0006] Some researchers have tried to alleviate the problem of the existing lithium layer covering the entire composite surface by setting a continuous lithium coating layer on both sides of the substrate with an intermittent lithium coating layer in the middle. This method improves the uniformity of the lithium layer to a certain extent, but there are still obvious shortcomings. Since only part of the negative electrode has a lithium layer, the area without a lithium layer cannot be pre-lithiated, which will lead to inconsistent battery performance. In addition, the uneven thickness of the electrode will also cause problems such as equipment belt deviation, affecting the manufacturing quality and consistency of the battery.

[0007] Therefore, in response to the above problems, the inventors believe that how to use molten metal to continuously and evenly coat the substrate is the focus of the present invention. At the same time, in view of the obvious difference in melting points between lithium and copper foil, how to further improve the wettability between the molten metal and the substrate and achieve the preparation of ultra-thin lithium metal by coating molten lithium liquid metal on the surface of copper foil is also a problem that we need to further consider. Summary of the invention

[0008] The present invention aims at the problems in the prior art, fully considers how to ensure high-precision and high-efficiency continuous and uniform coating of multiple lithium strips on a substrate, and discloses a composite strip and a preparation method and manufacturing equipment thereof.

[0009] The present invention is achieved through the following technical solutions:

[0010] In a first aspect, the present invention provides a composite tape; the composite tape comprises a substrate and a coating layer; the coating layer is located on the substrate; the coating layer is continuously arranged along the length direction of the substrate and is arranged at intervals in the width direction of the substrate; the thickness of the coating layer is selected from 0.1 to 100 μm;

[0011] As a further solution, the thickness of the coating layer is preferably from 0.1 to 5 μm;

[0012] Furthermore, the thickness of the coating layer is preferably from 0.1 to 3 μm;

[0013] Further, the coating layer is selected from a metal coating layer;

[0014] Furthermore, the substrate is selected from one or more of metal foil, a lithium battery positive electrode sheet, a lithium battery negative electrode sheet, a sodium battery positive electrode sheet or a sodium battery negative electrode sheet.

[0015] Furthermore, the metal foil is selected from a metal-containing foil layer; as some specific examples: the metal-containing foil is selected from one or more of copper, aluminum, nickel, and tin; or it is a metal-containing foil formed by a composite of one or more non-metallic elements selected from carbon, silicon, boron, and phosphorus and one or more metal elements selected from copper, aluminum, nickel, and tin.

[0016] Furthermore, the metal coating layer is a metal coating layer composed of one or more metals selected from potassium, sodium, indium, lithium, zinc, lead, silicon, and tin, or alloys thereof and conductive additives;

[0017] Furthermore, the metal coating layer is preferably one or more selected from lithium and sodium;

[0018] Furthermore, the conductive additive is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, conductive polymer, and metal conductive agent; and the proportion of the conductive additive is selected from 0.01-50%.

[0019] In a second aspect, the present invention provides a composite tape manufacturing device, comprising the composite tape according to the first aspect; the composite tape manufacturing device comprises:

[0020] A conveying system for continuously conveying the substrate;

[0021] A coating mechanism, comprising a die head, wherein the die head is used to coat the continuously conveyed substrate with a molten liquid under a protective atmosphere;

[0022] The melt conveying system is used to convey the melt to the die head under a protective atmosphere;

[0023] A cooling and shaping mechanism, used for cooling and shaping the coated substrate;

[0024] A calendering mechanism, used for calendering the substrate after cooling and shaping;

[0025] The coating mechanism, the cooling and shaping mechanism, and the calendering mechanism are sequentially arranged along the conveying direction of the substrate.

[0026] As a further solution, the die head comprises an upper die head and a lower die head; the upper die head and the lower die head are covered to form a hollow liquid storage tank;

[0027] The liquid storage tank is provided with a rotatable stirring device inside;

[0028] Both ends of the stirring device are also provided with detachable sealing devices; at least one of the sealing devices is provided with a high-pressure protective gas inlet connected to the liquid storage tank.

[0029] As a further solution, the upper die head and the lower die head are respectively provided with ports at the end positions of the liquid storage tank for allowing the stirring device to pass through, the inner wall of the port is provided with an inner wall groove, and the stirring device is provided with a groove matching and fitting with the inner wall groove for fixing the stirring device; the outer wall of the port is provided with an outer groove for fixing the sealing device;

[0030] Furthermore, the sealing device further comprises a sealing cover plate and a cover plate protrusion, wherein the sealing cover plate has a diameter larger than the cover plate protrusion and is integrated with the cover plate protrusion; the cover plate protrusion is sealingly plugged into an outer groove of an outer wall of the port;

[0031] Furthermore, the sealing cover plate is provided with the high-pressure protective gas inlet; at the same time, an air inlet channel corresponding to the high-pressure protective gas inlet is provided on the port, and the air inlet channel is connected with the inner wall groove to realize the air intake of the liquid storage tank.

[0032] As a further solution, the die head further comprises a gasket, which is arranged in the area between the liquid storage tank and the edge of the die head, and the gasket is provided with a gasket opening toward the edge of the die head, and the molten liquid is evenly distributed and discharged through the gasket opening; wherein, on the die head, the die head edge corresponding to one side of the gasket opening is the die head discharge port;

[0033] The die head also includes a fine-tuning mechanism; the fine-tuning mechanism is arranged on the upper die head; the die head also has a die head heating device;

[0034] Furthermore, at least two positioning pins are provided on the gasket, and the gasket is fixed on the die head by the positioning pins;

[0035] Furthermore, the fine-tuning mechanism includes an adjustment plate and at least two threaded screws arranged in parallel; the adjustment plate is provided with a threaded hole corresponding to the threaded screw, the threaded screw is connected to the adjustment plate through the threaded hole, the setting position of the adjustment plate can be relatively fixed with the position of the upper die head, and the adjustment free end of the threaded screw acts on the upper die head, and is used to change the opening size of the die head discharge port by applying a force to the upper die head.

[0036] As a further solution, the coating mechanism further includes a die stopper; the die stopper is movably arranged on one side of the die; and is used to cover the die when the die is not coated to prevent the die from leaking liquid;

[0037] Furthermore, the die head stopper includes a movable bracket and a baffle; the baffle is detachably arranged on the bracket and close to one side of the die head;

[0038] Furthermore, the die block also includes a block heating device, which is detachably arranged on the bracket and away from one side of the die;

[0039] Furthermore, a waste liquid collection tank is detachably provided below the baffle.

[0040] As a further solution, the molten liquid transmission system includes: a feeding and ventilation metering bin, a molten liquid tank, a molten liquid storage tank, and a protective gas tank;

[0041] Furthermore, one end of the protective gas tank is independently connected to the feeding and ventilation metering bin, the melting tank, and the melt storage tank; and the other end is connected to the high-pressure protective gas inlet on the die head;

[0042] Furthermore, the melt transfer system is also provided with a solution pump, through which the die head is fed;

[0043] Furthermore, the molten liquid transmission system further comprises a delivery pipe for sequentially connecting various parts of the molten liquid transmission system;

[0044] Furthermore, the molten liquid transmission system also includes a vacuum pump, which is connected to the material feeding and ventilation metering bin.

[0045] As some specific solutions, the manufacturing equipment may also have a substrate heating mechanism for heating the substrate before coating, which is beneficial to improving the wettability of the molten lithium and enhancing the bonding between the molten lithium and the substrate.

[0046] Furthermore, the substrate heating mechanism includes an upper component and a lower component; the upper component and the lower component cover each other to form a hollow chamber; a plurality of groups of rollers are arranged inside the chamber; the rollers are used to transport the substrate to ensure that the substrate can be evenly heated during the heating process.

[0047] Furthermore, the covering contact part of the upper component and the lower component is provided with a substrate inlet and a substrate outlet along the substrate conveying direction, so as to enable the substrate to enter the interior of the substrate heating mechanism for heating.

[0048] Furthermore, after the upper and lower components are closed, a hot air inlet and a hot air outlet are independently arranged on both sides of the exterior;

[0049] In principle, the present invention does not limit the specific location of the hot air inlet and the hot air outlet; those skilled in the art can select and design according to actual needs; as some examples: the hot air inlet can be set on the outside of the lower component, and the hot air outlet can be set on the outside of the upper component.

[0050] Furthermore, the substrate heating mechanism is also connected to a heating box, which is connected to the hot gas inlet of the substrate heating mechanism through a pipeline. The gas is heated by the heating box and then enters the interior of the substrate heating mechanism to heat the substrate.

[0051] The present invention does not limit the specific position of the heating box, and those skilled in the art can select and design it according to actual needs. As some examples, the present invention connects a heating box to the outside of the substrate heating mechanism to achieve heating of the substrate.

[0052] As a further solution, the conveying system includes an unwinding system and a rewinding system;

[0053] Furthermore, the unwinding system includes an unwinding shaft and at least one set of unwinding rolling rollers; the unwinding shaft is used to sleeve the substrate, and the unwinding rolling rollers are arranged between the unwinding shaft and the coating mechanism to achieve continuous supply of the substrate;

[0054] Furthermore, the winding system is arranged behind the calendering mechanism along the substrate conveying direction, and includes a winding shaft and at least one group of winding rolling rollers; the winding rolling rollers are arranged between the winding shaft and the calendering mechanism.

[0055] As a further solution, the cooling and shaping mechanism is arranged behind the coating mechanism along the substrate conveying direction, and is used to cool and shape the coated composite tape; the cooling and shaping mechanism includes at least one set of upper cooling rollers and lower cooling rollers arranged coaxially on the upper and lower sides of the substrate;

[0056] The calendering mechanism is arranged behind the cooling and shaping mechanism along the conveying direction of the substrate, and the calendering mechanism comprises at least one group of coaxially arranged pressing rollers on the upper and lower sides of the substrate.

[0057] As a further solution, the manufacturing equipment of the composite tape also includes a coding mechanism, which is arranged between the calendering mechanism and the winding system; the coding mechanism includes at least one group of tension rollers coaxially arranged on both sides of the substrate, and the coding mechanism also includes a coding rolling roller and an encoder.

[0058] In a third aspect, the present invention provides a method for preparing a composite tape; comprising the composite tape of the first aspect and the manufacturing equipment of the composite tape of the second aspect; the steps include:

[0059] S1: transporting the molten liquid to the die head under a protective atmosphere through the molten liquid transmission system;

[0060] S2: The die head stirs the molten liquid under a protective atmosphere and simultaneously coats the continuously transported substrate;

[0061] S3: Cooling and shaping the coated substrate;

[0062] S4: The substrate after cooling and shaping is subjected to calendering treatment to obtain a composite tape having multiple uniform continuous coating layers at the same time.

[0063] As some specific solutions, the substrate in S4 may also pass through a substrate heating mechanism before reaching the die outlet; specifically, the substrate passes through an unwinding mechanism, a substrate heating mechanism, and a die outlet in sequence for coating.

[0064] Furthermore, the temperature range of the substrate heating mechanism is 100-350 degrees.

[0065] As a further solution, when the die in S2 is not coating, a movable die stopper is used to cover the die outlet;

[0066] Further, the heating temperature of the die block is selected from 50-500°C;

[0067] Furthermore, the die head temperature range is selected from 100-500° C. during coating.

[0068] As a further solution, when cooling and shaping the substrate in S3, at least one set of upper cooling rollers and lower cooling rollers are respectively provided on the upper and lower sides of the substrate; wherein the temperature of the upper cooling rollers is selected from 15-150°C; the temperature of the lower cooling rollers is selected from 15-100°C; the relationship between the roller gap distance d between each set of upper cooling rollers and the lower cooling rollers and the total thickness D of the substrate after the die coating is completed is d=m D, and m is selected from 0.7-1.6;

[0069] Further, the temperature of the upper cooling roller is preferably selected from 20-50°C; the temperature of the lower cooling roller is selected from 20-30°C;

[0070] Furthermore, the calendering process in S4 is achieved by at least one set of coaxially arranged pressure rollers on the upper and lower sides of the substrate, and the relationship between the roller gap distance y between each set of pressure rollers and the total thickness Y of the substrate after cooling and shaping is y=nY, where n is selected from 0.5-1.3;

[0071] The temperature range of the pressure roller is selected from 80-200°C.

[0072] The characteristics and beneficial effects of the present invention are:

[0073] In terms of composite belts:

[0074] The composite tape prepared by the present invention has a continuous and uniform coating layer, and can simultaneously form multiple coating layers in the width direction of the substrate; the spacing distance between the coating layers can be adjusted. In addition, the thickness of the composite tape provided by the present invention can be reduced to a minimum of 0.1 μm under the premise of ensuring continuity and uniformity, which effectively reduces the amount of lithium used while ensuring the performance and safety of the battery. Compared with the prior art where the lithium layer is excessively coated, discontinuous and uneven, and the negative electrode sheet needs to be split multiple times for calendering pre-lithiation, the present invention provides a more efficient and safe solution strategy; using the composite tape of the present invention, the first coulomb efficiency of the battery is effectively improved during the test process, the irreversible loss of lithium is reduced, the cycle stability of the battery is enhanced and its service life is extended.

[0075] In terms of manufacturing equipment:

[0076] The manufacturing equipment of the present invention has a die head; under the combined action of a protective atmosphere and a stirring device, the continuously conveyed substrate can be coated; the edge of the molten liquid can be prevented from solidifying and the molten liquid can be prevented from being oxidized and contaminated; the substrate surface can be continuously and evenly coated; thereby effectively avoiding the problems of uneven lithium powder dispersion and discontinuous lithium foil rolling and compounding in the traditional pre-lithiation method. At the same time, the die head of the present invention has a heating device to ensure that the molten metal material maintains appropriate fluidity during the coating process.

[0077] The die head in the manufacturing equipment of the present invention is also provided with a gasket opening, and the gasket opening is used for discharging and coating the molten liquid; the thickness, width and number of the gasket openings can be adjusted to achieve that the composite belt has multiple continuous and uniform coating layers at the same time, and the thickness and width of the coating layer are adjustable; in addition, the die head of the present invention is also provided with a fine-tuning mechanism; the thickness of the coating layer is accurately controlled to ensure the stability and repeatability of the coating quality. It provides a new solution for the pre-lithiation technology of lithium-ion batteries and sodium-ion batteries.

[0078] The present invention not only has a die head that can achieve continuous and uniform coating, but also includes a die head block for covering the die head when the die head is not coating. The die head block of the present invention has a heating device, which is beneficial to prevent the molten liquid from solidifying and blocking the die head outlet when the die head outlet is covered; and it is also beneficial to prevent air from entering and causing oxidation of the molten liquid; in addition, the die head block of the present invention also has a waste liquid collection tank, thereby maintaining the cleanliness of the equipment and the coating quality.

[0079] The present invention further performs cooling, shaping and calendering treatments on the substrate coated by the coating system; and further ensures the flatness and thickness uniformity of the composite tape by controlling the temperature and roller gap of the cooling roller and the stretching roller, and further eliminates surface scratches in the preparation of the composite tape. In addition, the manufacturing equipment of the present invention is easy to operate, can greatly improve production efficiency, reduce production costs, and achieve continuous production of composite tapes. Through these technical solutions, the present invention not only solves the problems of uneven and discontinuous pre-lithiation in the prior art, but also significantly improves the performance of the battery. In addition, the manufacturing equipment provided by the present invention can also be applied to the coating of other metal melts on substrates to prepare composite tapes with composite requirements, and has high industrial practical value.

[0080] In addition, the manufacturing equipment of the present invention further adds a substrate heating mechanism, which helps to further improve the wettability between the substrate and the molten metal by heating the substrate, so that the molten metal is evenly and stably present on the surface of the substrate, thereby achieving the preparation of a thinner and more uniform metal coating layer.

[0081] In terms of preparation method:

[0082] The present invention effectively prevents the solidification of molten metal and the blocking of the die head by regulating the heating temperature of the die head and the die head block; it is conducive to the preparation of a continuous and uniform coating layer; at the same time, by setting the temperature of the cooling roller and the extension roller and the roller gap distance, the flatness and thickness uniformity of the composite belt are further ensured, which provides good operating conditions for the preparation of composite belts mainly composed of lithium and sodium in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0084] Figure 1 is a schematic diagram of the melt transfer system in Examples 1-11 of the present invention;

[0085] Figure 2 is a schematic diagram of a manufacturing device for a composite tape in Examples 1-10 of the present invention;

[0086] Figure 3 It is a schematic diagram of the structure of the die head in Examples 1-11 of the present invention;

[0087] Figure 4 is a schematic diagram of a local structure of a fine-tuning structure in Embodiments 1-11 of the present invention;

[0088] Figure 5 It is a schematic diagram of the partial structure of the die head in Examples 1-11 of the present invention;

[0089] Figure 6 It is a schematic diagram of the partial structure of the die head in Examples 1-11 of the present invention;

[0090] Figure 7 It is a schematic diagram of the structure of the die block in Examples 1-11 of the present invention;

[0091] Figure 8 is a schematic diagram of the structure of the gasket in Examples 1-11 of the present invention;

[0092] Fig. 9 is a schematic diagram of the structure of the composite belt in Examples 1-11 of the present invention;

[0093] Fig.10 It is a schematic diagram of the partial structure of the die head in Examples 1-11 of the present invention;

[0094] Fig.11 is a schematic diagram of a manufacturing device for a composite belt in Example 11 of the present invention;

[0095] Fig.12 is a schematic structural diagram of a substrate heating mechanism in Example 11 of the present invention;

[0096] Fig.13 is a partial structural schematic diagram of a substrate heating mechanism in Example 11 of the present invention;

[0097] Fig.14 is the contact angle of the molten metal when coated on the substrate in Example 1 of the present invention;

[0098] Fig.15 It is the contact angle of the molten metal when it is coated on the substrate heated by the substrate heating mechanism in Example 11 of the present invention.

[0099] Reference numerals:

[0100] Substrate 1; coating layer 11;

[0101] Conveying system 2; unwinding system 21; winding system 22; unwinding shaft 211; unwinding rolling roller 212; winding shaft 221; winding rolling roller 222;

[0102] Coating mechanism 3; die head 31; upper die head 311; lower die head 312; liquid storage tank 313; stirring device 314; sealing device 315; high-pressure protective gas inlet 3151; stirring rod 3141; stirring shaft 3142; transmission device 3143; port 3131; inner wall groove 31311; channel 31312; outer groove 31313; sealing cover plate 3152; cover plate protrusion 3153; air inlet channel 3154; gasket 316; gasket opening 3161; die outlet 317; positioning pin 3162; fine adjustment mechanism 318; adjustment plate 3181; threaded screw 3182; threaded hole 3183; fixing device 319; die heating device 33; die stopper 32; bracket 321; stopper 322; stopper heating device 323; waste liquid collection tank 324; die feed inlet 331; die return port 332;

[0103] Molten liquid transmission system 4; feeding and ventilation metering bin 41; melting tank 42; molten liquid storage tank 43; protective gas tank 44; solution pump 45; delivery pipe 46; vacuum pump 47;

[0104] Cooling and shaping mechanism 5; upper cooling roller 51; lower cooling roller 52;

[0105] Calendering mechanism 6; pressing roller 61;

[0106] Encoding mechanism 7; tension roller 71; encoding rolling roller 72; encoder 73;

[0107] Substrate heating mechanism 8; upper component 81; lower component 82; roller 83; substrate inlet 84; substrate outlet 85; hot air inlet 86; hot air outlet 87; heating box 88. DETAILED DESCRIPTION

[0108] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below, and embodiments of the present invention are given, but the scope of the present invention is not limited thereby.

[0109] In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0110] Normally, we refer to materials that need to be coated with molten metal as substrates; the inventors of the present invention have conducted research on new pre-lithiation technology; in the hope of solving the problems of using lithium powder or lithium metal composite tape to prepare composite tapes for substrates 1 that need to be pre-lithiated in the prior art, which is prone to excessive lithium, discontinuous lithium layers, and uneven pre-lithiation; through the research of the present invention, it is found that the use of molten liquid to coat substrate 1 is more convenient and controllable; it is expected to alleviate the problem of discontinuous or uneven pre-lithiation. However, as a fluid, the molten liquid is the focus of exploration and research on its fluidity, uniformity, and oxidizability when coating substrate 1. Based on this, the present invention has conducted new pre-lithiation technology, and proposed a composite tape preparation device and manufacturing method, hoping to prepare a composite tape with multiple continuous and uniform lithium layers at the same time.

[0111] Reference Figure 1-13 ; In the first aspect, the present invention provides a composite tape; the composite tape comprises a substrate 1 and a coating layer 11; the coating layer 11 is located on the substrate 1; the coating layer 11 is continuously arranged along the length direction of the substrate 1 and is arranged at intervals in the width direction of the substrate 1; the thickness of the coating layer 11 is selected from 0.1 to 100 μm.

[0112] Specifically, the spacing distance of the coating layer 11 is consistent with the distance between every two gasket openings 3161 of the gasket 316 of the die head 31 , and the thickness of the coating layer 11 is consistent with the thickness of each gasket opening 3161 .

[0113] The composite tape prepared by the present invention has a continuous and uniform coating layer 11, and multiple coating layers 11 can be prepared simultaneously in the width direction of the substrate 1; the spacing distance of the coating layers 11 can be adjusted accordingly as needed. In addition, the composite tape provided by the present invention can have a minimum thickness of 0.1 μm on the basis of achieving continuity and uniformity, and the thickness can be adjusted, which is convenient for customization according to needs; thereby significantly reducing the amount of metal used, while ensuring the performance and safety of the battery. For example, when using a graphite negative electrode, a negative electrode with a low silicon-carbon content, or a thinner negative electrode sheet, only 1-2μm of lithium supplementation is required; while the rolling process of composite tapes based on lithium tapes on the market can only produce a thickness of about 5μm. When rolling to produce a lower thickness, due to the strong ductility of lithium metal and the soft material, it is difficult to roll to produce a thinner lithium tape, which is prone to rupture and breakage; and the coating layer prepared by the present invention, taking lithium and its alloy or conductive agent composite layer as an example, can be of different thicknesses such as 3μm, 7μm, 14μm or 17μm; and thinner coatings such as 0.1μm and 2μm can be produced by adjusting the equipment. This provides a more efficient and safe solution to the problems in the prior art of excessive, discontinuous and uneven lithium layer coating, which requires multiple splitting of the negative electrode sheet for pre-lithiation by rolling; the composite belt of the present invention can achieve uniform pre-lithiation of the battery negative electrode material, thereby improving the battery's initial coulombic efficiency, reducing the irreversible loss of lithium, enhancing the battery's cycle stability and extending the battery's service life; at the same time, it can flexibly adapt to the needs of different battery designs, providing a larger design space for battery manufacturing.

[0114] As some specific solutions, the thickness of the coating layer 11 is preferably from 0.1 to 5 μm;

[0115] Furthermore, the coating layer 11 preferably has a thickness of 0.1 to 3 μm.

[0116] The present invention does not impose any particular restriction on the material of the substrate 1. When the battery is pre-lithiated, the substrate 1 is selected from one or more of metal foil, lithium battery positive electrode sheet, lithium battery negative electrode sheet, sodium battery positive electrode sheet or sodium battery negative electrode sheet.

[0117] Furthermore, the metal foil is selected from metal-containing foil; as some specific examples: the metal-containing foil is selected from one or more metal foils of copper, aluminum, nickel, and tin; or the metal-containing foil is formed by a composite of one or more non-metallic elements of carbon, silicon, boron, and phosphorus and one or more metal elements of copper, aluminum, nickel, and tin.

[0118] Take the preparation of lithium composite tape by pre-lithiation as an example; after the substrate is coated with molten lithium using the device of the present invention, on the one hand, the composite tape prepared by the substrate coated with molten lithium can be directly coated with active materials to be prepared into battery pole pieces for use; on the other hand, the substrate can also be used as a transfer tape; after the composite tape is prepared by coating molten lithium on the substrate; the lithium tape on the composite tape is transferred separately and transferred to the pole piece by calendering treatment or the like, and the substrate can be reused for coating and transfer of molten lithium.

[0119] As some specific solutions, the coating layer 11 is selected from a metal coating layer.

[0120] Furthermore, the metal coating layer is selected from one or more metals selected from potassium, sodium, indium, lithium, zinc, lead, silicon, and tin, or their alloys and a conductive additive. For lithium batteries that require pre-lithiation, the coating layer 11 of the composite tape uses molten metallic lithium.

[0121] Furthermore, the conductive additive is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, conductive polymer, and metal conductive agent; the proportion of the conductive additive is selected from 0.01-50%.

[0122] As some specific solutions, the metal coating layer is preferably one or more metals selected from lithium and sodium.

[0123] In the preparation process of the composite tape of the present invention, in order to further improve the bonding strength between the coating layer and the substrate and avoid oxidation of the molten metal, additives may be added to the molten metal or the surface of the substrate; the additives may include metal antioxidants or flux; wherein the metal antioxidant may be selected from phosphates (exemplary such as: sodium dihydrogen phosphate, sodium phosphite, sodium citrate, etc.), silicates (exemplary such as: sodium silicate, calcium silicate, etc.), borates (exemplary such as: potassium borate, sodium borate, etc.), organic metal antioxidants (exemplary such as: organic tin, organic cobalt, etc.); the flux may be selected from one or more of organic solvents, rosin resins and their derivatives.

[0124] The manufacturing equipment of the present invention is particularly suitable for the preparation of lithium composite belts and sodium composite belts; molten lithium and molten sodium metals have serious beading phenomenon during the preparation process, large surface tension and easy oxidation; and the equipment of the present invention effectively solves these problems by arranging a stirring device and protective gas inside the die head, and adding die head blocks, cooling, extension and other structures. The stirring device arranged inside the die head can ensure the uniform distribution of the molten metal and prevent the occurrence of beading phenomenon; the use of protective gas can effectively isolate the air and reduce the oxidation of the metal; the addition of die head blocks helps to control the flow direction of the molten metal and the thickness of the coating layer; the cooling and extension structures ensure that the coating layer can shrink evenly during the cooling process, avoiding the generation of cracks. Through the optimized combination of these structures, the equipment of the present invention can prepare a composite belt with uniform thickness and good adhesion, meeting the strict requirements for the pre-lithiation layer in battery manufacturing.

[0125] In a second aspect, the present invention provides a composite tape manufacturing device, comprising the composite tape described in the first aspect;

[0126] The manufacturing equipment comprises:

[0127] A conveying system 2, used for continuously conveying the substrate 1;

[0128] The coating mechanism 3 comprises a die head 31, wherein the die head 31 is used to coat the continuously conveyed substrate 1 with a molten liquid under a protective atmosphere;

[0129] The melt conveying system 4 is used to convey the melt to the die head 31 under a protective atmosphere;

[0130] A cooling and shaping mechanism 5, used for cooling and shaping the coated substrate 1;

[0131] The calendering mechanism 6 is used to calender the substrate 1 after cooling and shaping.

[0132] The coating mechanism 3 , the cooling and shaping mechanism 5 , and the calendering mechanism 6 are sequentially arranged along the conveying direction of the substrate 1 .

[0133] Through the coordinated work of the above mechanisms, coating of the substrate 1 is achieved.

[0134] As some specific solutions, the die head 31 includes an upper die head 311 and a lower die head 312; the upper die head 311 and the lower die head 312 are covered to form a hollow liquid storage tank 313 for storing the molten liquid;

[0135] The liquid storage tank 313 has a rotatable stirring device 314 inside for stirring the molten liquid;

[0136] The two ends of the stirring device 314 are also provided with a detachable sealing device 315, which is used to seal the liquid storage tank 313 when the die head 31 is in the closed state, so as to prevent the molten liquid in the liquid storage tank 313 from leaking and oxidizing, which would affect the preparation of the composite tape.

[0137] At least one of the sealing devices 315 is provided with a high-pressure protective gas inlet 3151 connected to the liquid storage tank 313; it is used to introduce protective gas into the die head 31 to ensure that the molten liquid in the liquid storage tank 313 is always fed and discharged from the die head 31 under a protective atmosphere; it prevents oxidation and contamination of the molten liquid, and realizes uniform and continuous coating of the molten liquid to prepare a composite tape.

[0138] As some specific schemes, the stirring device 314 includes a stirring rod 3141 and a stirring shaft 3142 for driving the stirring rod 3141 to rotate; the stirring rod 3141 is accommodated inside the liquid storage tank 313, and is used to stir the molten liquid to prevent the molten liquid from precipitating, edge solidification or unevenness during the coating process, thereby ensuring the continuity and consistency of the coating layer 11.

[0139] As some specific solutions, the stirring rod 3141 and the stirring shaft 3142 are fixedly connected, and the rotation of the stirring device 314 is realized by an external transmission device 3143. In principle, the present invention does not limit the connection method between the stirring rod 3141 and the stirring shaft 3142 or the connection method of the external transmission device 3143, and those skilled in the art can select a suitable connection method according to needs; for example, the stirring rod 3141 and the stirring shaft 3142 can be connected by thread, welding, key or other mechanical connection methods; the transmission device 3143 for realizing the rotation of the stirring device 314 can be set inside or outside the stirring device 314 and other suitable positions.

[0140] The width and length of the stirring rod 3141 are not limited in principle, but it is preferred that the stirring rod 3141 can basically cover the entire space of the liquid storage tank 313, and avoid direct contact between the stirring rod 3141 and the wall of the liquid storage tank 313, so as to reduce the wear of the molten liquid on the wall of the liquid storage tank 313 during the stirring process and ensure a comprehensive stirring effect. Those skilled in the art can select a suitable length and width design according to actual needs. For example, the width and length of the stirring rod 3141 can be designed to occupy 60%-95% of the diameter and length of the space of the liquid storage tank 313, respectively.

[0141] As some specific solutions, the shape of the stirring rod 3141 is not limited, and exemplary shapes can be selected from one or more of rectangular, square, circular, and elliptical.

[0142] As some specific solutions, the upper die head 311 and the lower die head 312 are respectively provided with ports 3131 at the end positions of the liquid storage tank 313, through which the stirring device 314 can pass, and the inner wall of the port 3131 is provided with an inner wall groove 31311, and the stirring device 314 is provided with a groove 31312 matching and fitting with the inner wall groove 31311, so that the stirring device 314 can be rotated and fixed on the port 3131; specifically, it is provided on the stirring shaft 3142 of the stirring device 314. The outer wall of the port 3131 is provided with an outer groove 31313, which is used to fix the sealing device 315 to achieve sealing of the die head 31.

[0143] As some specific schemes, the sealing device 315 also includes a sealing cover plate 3152 and a cover plate protrusion 3153. The sealing cover plate 3152 has a diameter larger than the cover plate protrusion 3153 and is integrated with the cover plate protrusion 3153. The cover plate protrusion 3153 is sealed and plugged with the outer groove 31313 on the outer wall of the port 3131, thereby realizing mechanical sealing of the liquid storage tank 313, preventing the liquid storage tank 313 from leaking, solidification blockage, and air infiltration causing oxidation of the molten liquid, so as to facilitate the die head 31 to continuously and evenly coat the substrate 1 to prepare a composite tape.

[0144] As some specific schemes, the sealing cover plate 3152 is provided with the high-pressure protective gas inlet 3151; at the same time, the port 3131 is provided with an inlet channel 3154 corresponding to the high-pressure protective gas inlet 3151, and the inlet channel 3154 is connected to the inner wall groove 31311 to realize the air intake of the liquid storage tank 313.

[0145] As some specific schemes, the die 31 also includes a gasket 316, which is arranged in the area between the liquid storage tank 313 and the edge of the die. The gasket 316 is provided with a gasket opening 3161 toward the edge of the die, and the molten liquid is evenly distributed and discharged through the gasket opening 3161; on the die 31, the die edge corresponding to one side of the gasket opening 3161 is the die discharge port 317.

[0146] As some specific schemes, the number, thickness and width of the gasket openings 3161 are consistent with the number, thickness and width of the composite tape coating layer 11; when the molten liquid is discharged through the gasket openings 3161 to coat the continuously conveyed substrate 1, the preparation of coating layers 11 with different numbers, thicknesses and widths on the substrate 1 can be achieved by adjusting the number, thickness and width of the gasket openings 3161; thereby, a composite tape with multiple continuous and uniform coating layers 11 is obtained.

[0147] As some specific solutions, at least two positioning pins 3162 are provided on the gasket 316 , and the positioning pins 3162 are used to fix the gasket 316 on the die head 31 .

[0148] In principle, the present invention does not limit the number, width and length of the gasket opening 3161. Those skilled in the art can make corresponding settings according to the different thicknesses of the coating layer 11, the number of strips distributed in parallel on the substrate 1, and the width; thereby achieving continuous and uniform coating on the substrate 1, thereby preparing a composite belt having multiple coating layers 11 at the same time.

[0149] As some specific solutions, the shape of the gasket opening 3161 is not limited. The exemplary shape can be selected from one or more shapes of straight line, wave, and arc to meet different coating requirements and effects.

[0150] As some specific solutions, the die 31 also includes a fine-tuning mechanism 318; the fine-tuning mechanism 318 is arranged on the upper die 311, specifically, it can be above the die outlet 317, and the size of the die outlet 317 is fine-tuned by the fine-tuning mechanism 318 to adapt to the coating requirements of substrates 1 and molten liquid of different thicknesses, and prepare a uniform and continuous composite belt. The design of the fine-tuning mechanism 318 enables the operator to accurately control the thickness of the coating layer 11, thereby realizing precise control of the thickness of the lithium layer of the composite belt. In addition, the addition of the fine-tuning mechanism 318 also improves the flexibility and applicability of the equipment, enabling it to adapt to production requirements of different specifications.

[0151] As some specific schemes, the fine-tuning mechanism 318 includes an adjustment plate 3181 and at least two threaded screws 3182 arranged in parallel; the adjustment plate 3181 is provided with a threaded hole 3183 corresponding to the threaded screw 3182, and the threaded screw 3182 is connected to the adjustment plate 3181 through the threaded hole 3183. The setting position of the adjustment plate 3181 can be relatively fixed with the position of the upper die head 311, and the adjustment free end of the threaded screw 3182 acts on the upper die head 311, and is used to change the opening size of the die head discharge port 317 by applying a force to the upper die head 311 to adapt to the coating requirements of substrates 1 and molten liquids of different thicknesses.

[0152] Furthermore, the adjustment plate 3181 can be fixed relative to the upper die head 311 by an external fixing device 319. The present invention does not limit the device for fixing the adjustment plate 3181 in principle; those skilled in the art can select a suitable fixing device 319 and setting position as needed.

[0153] As some specific solutions, the die head 31 also has a die head heating device 33; the die head heating device 33 is used to provide the temperature of the die head 31 to prevent the molten liquid from solidifying.

[0154] The present invention does not limit the specific position, method and number of the die head heating device 33, and those skilled in the art can select and design it according to actual needs; the setting position of the die head heating device 33 of the present invention is preferably accommodated in the hollow cavity opened inside the die head 31; for example, a heating device can be respectively set in the upper die head 311 and the lower die head 312, which can ensure the uniform temperature of the die head 31, further improve the uniformity and quality of the coating, and prevent the molten liquid from solidifying. The heating devices of the upper die head 311 and the lower die head 312 can be independently controlled to meet the heating requirements of different molten liquids.

[0155] The die 31 of the present invention further includes a die feed port 331 and a die return port 332; the molten liquid transmission system 4 connects the die feed port 331 and the die return port 332 to realize feeding of the die 31 when the die 31 is coating, and when the die 31 stops coating, the molten liquid in the die 31 flows back to the molten liquid storage tank 43, so as to realize the circulation of the molten liquid in the transmission system. In principle, the present invention does not limit the specific setting positions of the die feed port 331 and the die return port 332; those skilled in the art can select and design according to actual needs; as some examples: the die feed port 331 can be set on the side of the upper die 311, and the die return port 332 can be set on the side of the lower die 312.

[0156] As some specific solutions, the coating mechanism 3 further includes a die stopper 32; the die stopper 32 is movably arranged on one side of the die, and is used to cover the die 31 when the die 31 is not coated, so as to prevent the die 31 from leaking liquid;

[0157] As some specific solutions, the die block 32 includes a movable bracket 321 and a baffle 322; the baffle 322 is detachably arranged on the bracket 321 and close to one side of the die 31, and is used to cover the discharge side of the die 31 to prevent leakage, oxidation and curing blockage.

[0158] The present invention arranges the bracket 321 movably on the fixing device 319, and realizes the movement of the bracket 321 by adjusting the fixing device 319; the present invention does not limit the method and position of the movement of the bracket 321, and those skilled in the art can make different choices for the position of the movement of the bracket 321 and the fixing device 319 according to actual needs.

[0159] As some specific solutions, the die block 32 also includes a block heating device 323, which is detachably arranged on the bracket 321 and away from one side of the die 31; it is used to provide heating temperature, maintain the fluidity of the molten liquid, and prevent the molten liquid from solidifying.

[0160] As some specific solutions, the die stopper 32 is movably arranged on one side of the die outlet 317 of the die 31 .

[0161] As some specific solutions, a waste liquid collection tank 324 is detachably provided under the baffle 322 to collect excess molten liquid.

[0162] As some specific schemes, the molten liquid transmission system 4 includes: a feeding and ventilation metering bin 41, a melting tank 42, a molten liquid storage tank 43, and a protective gas tank 44; one end of the protective gas tank 44 is independently connected to the feeding and ventilation metering bin 41, the melting tank 42, and the molten liquid storage tank 43, so as to protect the molten liquid and prevent the molten liquid from being oxidized; the other end is connected to the high-pressure protective gas inlet 3151 on the die head 31, so as to protect the molten liquid inside the die head 31;

[0163] The feeding, ventilation and metering bin 41 is used to add materials under the protection of protective gas;

[0164] The melting tank 42 is used to receive the material from the feeding and ventilation bin for melting treatment under the action of the protective gas;

[0165] The molten liquid storage tank 313 is responsible for receiving the molten liquid from the molten tank 42 under the action of the protective gas, and conveying the molten liquid to the die head 31, so as to realize the continuous liquid feeding of the die head 31 to coat the substrate 1 and prepare a composite tape with a uniform and continuous coating layer 11.

[0166] As some specific solutions, the molten liquid transfer system 4 is further provided with a solution pump 45 , and the solution pump 45 is used to feed the die head 31 .

[0167] As some specific solutions, the molten liquid transmission system 4 also includes a delivery pipe 46, which is used to sequentially connect various parts of the molten liquid transmission system 4 to achieve smooth molten liquid transmission.

[0168] As some specific solutions, the molten liquid transmission system 4 also includes a vacuum pump 47, which is connected to the feeding and ventilation metering bin 41 to ensure the pressure stability in the feeding and ventilation metering bin 41 and prevent air from entering the system to cause oxidation of the molten liquid. The vacuum pump 47 and the delivery pipe 46 work together to achieve full coverage of the protective gas in the entire molten liquid transmission system 4.

[0169] The molten liquid transmission system 4 and the die head 31 are fully covered with protective gas, which is conducive to effectively preventing the molten liquid from coming into contact with air and being oxidized during the transportation process, thereby extending the service life of the molten liquid and improving the quality of the composite belt. On the other hand, the protective gas covering the inside of the die head 31 is conducive to solving the problems of oxidation, corrosion, and high-precision coating of the molten metal; at the same time, the input of protective gas into the die head 31 also plays the role of protective gas sealing, effectively ensuring that the entire molten liquid transmission mechanism is in a protective gas environment; it is conducive to ensuring good adhesion between the coating layer 11 and the substrate 1 when coating the substrate 1. In addition, the use of protective gas can also reduce the volatilization loss of the molten liquid during the coating process, further improving the material utilization rate.

[0170] As some specific solutions, the manufacturing equipment may also have a substrate heating mechanism 8, which is used to heat the substrate 1 before coating, which is beneficial to improving the wettability of the molten lithium and enhancing the bonding between the molten lithium and the substrate 1.

[0171] Furthermore, the substrate heating mechanism 8 includes an upper component 81 and a lower component 82; the upper component 81 and the lower component 82 cover each other to form a hollow chamber; a plurality of groups of rollers 83 are arranged inside the chamber; the rollers 83 are used to transport the substrate 1 to ensure that the substrate 1 can be evenly heated during the heating process.

[0172] Furthermore, the upper component 81 and the lower component 82 cover and contact the part thereof and are provided with a substrate inlet 84 and a substrate outlet 85 along the conveying direction of the substrate 1 , so as to enable the substrate 1 to enter the interior of the substrate heating mechanism 8 for heating.

[0173] Furthermore, after the upper component 81 and the lower component 82 are closed, a hot air inlet 86 and a hot air outlet 87 are independently provided on both sides of the outside;

[0174] In principle, the present invention does not limit the specific location of the hot air inlet 86 and the hot air outlet 87; those skilled in the art can select and design according to actual needs; as some examples: the hot air inlet 86 can be set on the outside of the lower component 82, and the hot air outlet 87 can be set on the outside of the upper component 81.

[0175] Furthermore, the substrate heating mechanism 8 is also connected to a heating box 88, which is connected to the hot air inlet 86 of the substrate heating mechanism 8 through a pipeline. The gas is heated by the heating box 88 and then enters the interior of the substrate heating mechanism 8 to heat the substrate 1.

[0176] The present invention does not limit the specific position of the heating box, and those skilled in the art can select and design it according to actual needs. As some examples, the present invention connects a heating box 88 to the outside of the substrate heating mechanism 8 to achieve heating of the substrate 1.

[0177] The present invention further optimizes the equipment process for the lithium coating layer mainly composed of lithium; before the substrate is coated with the lithium melt, the substrate is further heated, and when the lithium melt is coated on the heated substrate, the contact angle of the lithium melt can be reduced, thereby strengthening the bonding between the coating layer and the substrate, and then through subsequent cooling, shaping and stretching treatment, the coating layer can achieve a thinner thickness and a more uniform and smooth coating layer, and it is helpful to eliminate scratches, thereby obtaining a better preparation effect.

[0178] As some specific solutions, the conveying system 2 includes an unwinding system 21 and a rewinding system 22; through the cooperation of the unwinding system 21 and the rewinding system 22, continuous conveyance of the substrate 1 is achieved.

[0179] Furthermore, the unwinding system 21 includes an unwinding shaft 211 and at least one group of unwinding rolling rollers 212; the unwinding shaft 211 is used to sleeve the substrate 1, and the unwinding rolling rollers 212 are arranged between the unwinding shaft 211 and the coating mechanism 3, so as to realize the continuous supply of the substrate 1; at the same time, the tension of the substrate 1 is kept even, ensuring that the substrate 1 runs smoothly during the coating process, avoiding relaxation or breakage, thereby ensuring the flatness and quality of the coating layer 11.

[0180] Furthermore, the winding system 22 is arranged behind the calendering mechanism 6 along the conveying direction of the substrate 1, and is used to wind up the prepared composite tape; the winding system 22 includes a winding shaft 221 and at least one group of winding rollers 222; the winding shaft 221 is used to realize the winding of the substrate 1, and the winding roller 222 is arranged between the winding shaft 221 and the calendering mechanism 6, and is used to maintain uniform tension of the composite tape during the winding process, ensuring that the wound composite tape is flat and wrinkle-free.

[0181] As some specific solutions, the cooling and shaping mechanism 5 is arranged behind the coating mechanism 3 along the conveying direction of the substrate 1, and is used to cool and shape the coated composite tape. The cooling and shaping mechanism 5 includes at least one set of upper cooling rollers 51 and lower cooling rollers 52 arranged coaxially on the upper and lower sides of the substrate 1, and is used to quickly cool and shape the coated substrate 1 to ensure the shape and size stability of the coating.

[0182] As some specific schemes, the calendering mechanism 6 is arranged behind the cooling and shaping mechanism 5 along the conveying direction of the substrate 1, and is used to further calender the substrate 1 that has been cooled and shaped after coating, so as to improve the flatness and adhesion of the coating. The calendering mechanism 6 includes at least one set of coaxially arranged pressure rollers 61 on the upper and lower sides of the substrate 1, and these pressure rollers 61 can be adjusted independently to adapt to composite strips of different thicknesses and materials; by accurately controlling the pressure and speed of the pressure rollers 61, scratches on the surface of the coated substrate 1 can be further eliminated, and a composite strip with multiple continuous and uniform coating layers 11 can be prepared.

[0183] As some specific solutions, the manufacturing equipment of the composite tape further includes a coding mechanism 7, which is arranged between the calendering mechanism 6 and the winding system 22, and is used to encode the composite tape; the coding mechanism 7 includes at least one group of tension rollers 71 coaxially arranged on both sides of the substrate 1, which are used to further ensure the flatness of the substrate 1 and the stability and accuracy during the encoding process. The coding mechanism 7 also includes a coding rolling roller 72 and an encoder 73, which are used to achieve continuous rolling and encoding of the substrate 1.

[0184] In a third aspect, the present invention provides a method for preparing a composite tape; comprising the composite tape of the first aspect and the manufacturing equipment of the composite tape of the second aspect; the steps include:

[0185] S1: Add the raw material of the metal coating layer into the feeding and ventilation metering bin 41 under a protective atmosphere, and perform vacuum ventilation treatment on the feeding and ventilation metering bin 41 through a vacuum pump 47 to ensure that the raw material is added in an oxygen-free environment;

[0186] S2: The material enters the melting tank 42 through the conveying pipe 46 from the feeding and ventilation metering bin 41. The melted liquid is sequentially conveyed to the die head 31 through the conveying pipe 46 through the melt storage tank 43 and the solution pump 45 under the protective atmosphere;

[0187] S3: In a protective gas atmosphere, the molten liquid is heated and stirred by the heating device and the stirring device 314 in the die head 31;

[0188] S4: The substrate 1 is supplied through the unwinding system 21 and reaches below the die outlet 317; the melted molten liquid coats the substrate 1; when the coating is stopped, a die stopper 32 is placed on one side of the die outlet 317.

[0189] S5: The coated substrate 1 is rapidly cooled and formed by the cooling and forming mechanism 5; the cooled and formed substrate 1 is further calendered by the calendering mechanism 6; the substrate 1 is encoded by the encoding device; the calendered substrate 1 is wound by the winding system 22; and finally a composite tape with a coating layer 11 is obtained.

[0190] In the preparation method of the present invention, a continuous production process is adopted, which can realize continuous coating of the substrate, ensuring the uniformity and quality stability of the coating layer. At the same time, by setting the die heating temperature, cooling temperature, calendering temperature and roller gap distance when the substrate is continuously coated, it is ensured that the substrate can obtain consistent physical and mechanical properties after uniform coating. By optimizing the process parameters, the scrap rate in the production process can be effectively reduced, the production efficiency can be improved, and the production cost can be reduced. In addition, in the preparation method of the present invention, the entire production process is carried out in a protective atmosphere, which effectively prevents oxidation caused by the contact of the molten liquid with the air, and ensures the quality of the prepared composite tape.

[0191] As some specific schemes, the substrate 1 in S4 may also pass through the substrate heating mechanism 8 before reaching the die outlet 317; specifically, the substrate passes through the unwinding mechanism 21, the substrate heating mechanism 8, and the die outlet 317 in sequence for coating.

[0192] Furthermore, the temperature of the substrate heating mechanism 8 is in the range of 100-350 degrees.

[0193] As some specific solutions, when the die 31 in S2 is not coating, a movable die stopper 32 is used to cover the die outlet 317 to prevent leakage, solidification blockage and oxidation contamination of the molten liquid.

[0194] Furthermore, the heating temperature of the die block 32 is selected from 50-500°C.

[0195] The die block temperature within this temperature range is beneficial to avoid leakage and solidification when the die is covered when the die is not coated, and to prevent die blockage or low temperature from causing solidified particles to form, affecting the uniformity of composite tape preparation.

[0196] As some specific solutions, the temperature range of the die head 31 during coating is selected from 100-500° C. Selecting a suitable die head temperature is conducive to achieving uniform coating of the molten liquid, ensuring a uniform coating thickness on the surface of the substrate, thereby obtaining good physical and mechanical properties. In addition, a suitable die head temperature helps the molten liquid to have good fluidity and spreadability during the coating process, further improving the preparation quality of the composite tape.

[0197] As some specific schemes, when cooling and shaping the substrate 1 in S3, there are at least one group of upper cooling rollers 51 and lower cooling rollers 52 on the upper and lower sides of the substrate 1 respectively; wherein the temperature of the upper cooling roller 51 is selected from 15-150°C; the temperature of the lower cooling roller 52 is selected from 15-100°C; the relationship between the roller gap distance d between each group of upper cooling rollers 51 and the lower cooling roller 52 and the total thickness D of the substrate 11 after the die head 31 is completed is d=mD, and m is selected from 0.7-1.6.

[0198] Furthermore, the temperature of the upper cooling roller 51 is preferably selected from 20-50°C; the temperature of the lower cooling roller 52 is selected from 20°C-30°C.

[0199] The appropriate range of cooling roller temperature and roller gap distance is conducive to the rapid cooling and shaping of the molten liquid on the substrate after coating, reducing energy consumption in the production process; and the molten liquid has a large surface tension and is easy to condense beads, and rapid cooling and shaping helps prevent the generation of uneven coating of the molten liquid. By accurately controlling the temperature of the cooling roller and the roller gap distance, it is also possible to effectively avoid deformation of the substrate or excessive internal stress of the coating caused by too fast or too slow cooling speed. In addition, reasonable temperature and spacing settings can also ensure that the composite tape maintains appropriate tension during the cooling process, thereby improving the flatness and dimensional stability of the product.

[0200] As some specific schemes, the calendering treatment in S4 is achieved by at least one group of stretching rollers 61 coaxially arranged on the upper and lower sides of the substrate 1, and the relationship between the roller gap distance y between each group of stretching rollers 61 and the total thickness Y of the substrate 1 after cooling and shaping is y=nY, where n is selected from 0.5-1.3.

[0201] The temperature range of the pressure roller is selected from 80-200°C.

[0202] Selecting the appropriate range of calender roll temperature and roll gap distance can effectively eliminate stress concentration during the cooling and shaping process, avoid cracks or breaks inside the material; at the same time, further eliminate scratches on the surface of the composite belt and ensure a uniform coating layer.

[0203] As some specific schemes, there is also a coding operation between S4 and S5 for coding the substrate 1.

[0204] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0205] Example 1

[0206] Copper foil (thickness: 6 μm) is selected as the substrate 1, and lithium metal is used as the molten liquid; 2.0 kg of lithium metal is added to the feeding ventilation metering bin 41, and vacuum ventilation treatment is performed by a vacuum pump 47; the lithium metal enters the melting tank 42 (temperature: 280 degrees) and the molten liquid storage tank 43 (temperature: 280 degrees) through the conveying pipe 46 in turn; and then is transported to the die head 31 by the solution pump 45.

[0207] Under the protection of protective gas, the molten liquid is heated (temperature: 280 degrees) and stirred (rotation speed: 5r / min) by the heating device and stirring device 314 in the die 31; the die head stopper 32 (temperature: 200 degrees) is used to cover the die head discharge port 317; the copper foil is continuously supplied through the unwinding system 21, and when the copper foil reaches the bottom of the die head discharge port 317, the die head baffle 322 is moved and withdrawn to coat the copper foil with molten lithium metal.

[0208] After coating is completed, when the coated substrate 1 enters the cooling and shaping mechanism 5, it is quickly cooled and shaped by the cooling and shaping mechanism 5 (the temperature of the cooling roller 51 above the substrate 1: 50 degrees; the temperature of the cooling roller 51 below the substrate 1: 30 degrees; the roller gap of each group of cooling rollers 51 (9 μm).

[0209] Subsequently, the cooled and shaped substrate 1 is calendered by a calendering mechanism 6 (temperature of the stretching rollers 61 above and below the substrate 1: 130 degrees; gap of each set of stretching rollers 61: 7.5 μm; pressure of each set of stretching rollers 61: 0.5 tons).

[0210] Then, the calendered substrate 1 is subjected to encoding processing by passing through the encoding mechanism 7 .

[0211] Finally, the composite tape is rolled up by the rolling system 22 to complete the preparation of the composite tape with the lithium layer.

[0212] Example 2

[0213] The specific operation method and conditions are the same as those in Example 1; the difference is that the heating temperature of the die head 31 is 320 degrees.

[0214] Example 3

[0215] The specific operation method and conditions are the same as those in Example 1; the difference is that during the cooling and shaping process, the temperature of the upper cooling roller 51 is selected from 55 degrees; the temperature of the lower cooling roller 52 is selected from 35 degrees.

[0216] Example 4

[0217] The specific operation method and conditions are the same as those in Example 1; the difference is that during the cooling and shaping process, the gap between the shaping rollers of each group of cooling rollers is 10 μm.

[0218] Example 5

[0219] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the temperature of the upper and lower pressure rollers 61 in each group is selected to be 150 degrees.

[0220] Example 6

[0221] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the temperature of the upper and lower pressure rollers 61 in each group is selected to be 115 degrees.

[0222] Example 7

[0223] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the gap between the press rolls 61 of each group of press rolls 61 is 8 μm.

[0224] Example 8

[0225] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the pressure of each group of spreading rollers 61 is 0.2 tons.

[0226] Example 9

[0227] The specific operation method and conditions are the same as those in Example 1; the difference is that the composition of the melt is selected from Li: graphene = 1:0.05.

[0228] Example 10

[0229] The specific operation method and conditions are the same as those in Example 1, except that: the substrate 1 is selected from the negative electrode sheet of a sodium battery (mainly made of hard carbon) (thickness: 150 μm); sodium metal is used as a molten liquid; during the cooling and shaping treatment, the temperature of the upper cooling roller 51 is selected from 50 degrees; the temperature of the lower cooling roller 52 is selected from 30 degrees. The gap between the shaping rollers of each group of cooling rollers is 153 μm.

[0230] During the calendering process, the temperature of the upper and lower pressure rollers 61 in each group is selected to be 80 degrees. The gap between the pressure rollers 61 in each group of pressure rollers 61 is 146 μm. The pressure of the pressure rollers 61 is 0.5 tons.

[0231] Embodiment 11

[0232] The specific operation method and conditions are the same as those in Example 1; the difference is that: a substrate heating mechanism 8 is added before the substrate 1 is coated; the substrate passes through the unwinding system 21, the substrate heating mechanism 8, the coating mechanism 3, the cooling and shaping mechanism 5, the calendering mechanism 6, the encoding mechanism 7, and the winding system 22 in sequence to complete the preparation of the composite tape; the specific steps of the substrate passing through the substrate heating mechanism 8 are: the substrate 1 enters the interior of the substrate heating mechanism 8 through the substrate inlet 84, and then is output through the substrate outlet 85 under the conveyance of the roller 83; while the substrate is being conveyed by the roller 83, it is heated under the action of a protective gas at a temperature of 220±10 degrees.

[0233] Comparative Example 1

[0234] The specific operation method and conditions are the same as those in Example 1; the difference is that when the die head 31 coats the continuously supplied substrate 1, the molten liquid is not stirred.

[0235] Comparative Example 2

[0236] The specific operation method and conditions are the same as those in Example 1; the difference is that the heating temperature of the die head 31 is 40 degrees.

[0237] Comparative Example 3

[0238] The specific operation method and conditions are the same as those in Example 1; the difference is that when the die head 31 is not coated with liquid, the die head stopper 32 is not placed to cover the die head outlet 317.

[0239] Comparative Example 4

[0240] The specific operation method and conditions are the same as those in Example 1; the difference is that during the cooling and shaping process, the temperature of the upper cooling roller 51 and the lower cooling roller 52 are both selected to be 10 degrees.

[0241] Comparative Example 5

[0242] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the temperature of the upper and lower pressure rollers 61 in each group is selected to be 50 degrees.

[0243] Comparative Example 6

[0244] The specific operation method and conditions are the same as those in Example 1; the difference is that during the calendering process, the gap between the press rolls 61 of each group of press rolls 61 is 4.5 μm.

[0245] Comparative Example 7

[0246] The specific operation method and conditions are the same as those in Example 1; the difference is that: the manufacturing equipment and preparation steps of the present invention are not used; the conventional method of the prior art is used to roll and compound the negative electrode sheet of the lithium-ion battery with lithium foil; the specific steps are: a 5μm thick and 150μm wide lithium foil is placed on the negative electrode sheet of 122μm thick and 151μm wide, and then rolled and compounded by a rolling machine. During the rolling process, the temperature of the upper and lower rolling rollers 61 is set to room temperature, the roller gap between the rolling rollers 61 is 110μm, and the pressure of the rolling rollers 61 is 0.5 tons.

[0247] Specific tests and methods: The width is calculated by a laser measuring instrument through the difference in laser reflection spectra of different materials to obtain the width value of the coating material. The width variation range is automatically generated by referring to the set width center value. The thickness is calculated by a X-ray thickness gauge through the change in X-ray penetration intensity to obtain the thickness value and variation range.

[0248] Table 1

[0249]

[0250]

[0251]

[0252] Table 2

[0253]

[0254] It can be seen from the data in Table 1 and Table 2 that the coating width, thickness and size after finalization of Examples 1 to 10 are all within the specified range, indicating that the manufacturing equipment and preparation steps of the present invention can achieve a stable and uniform coating effect. A composite tape with a continuous and uniform coating layer 11 is obtained; the problems of uneven coating layer 11 and inconsistent thickness in the pre-lithiation of the pole piece in the prior art are effectively solved. In addition, it can be seen from Table 2 that the coulombic efficiency of the composite substrate 1 battery cell in the embodiment is generally high, and the cycle performance is good, indicating that the manufacturing method and manufacturing equipment of the present invention have significant advantages and high industrial application value in improving the quality of the composite tape, battery performance and production efficiency.

[0255] In contrast, when the die head is used unreasonably in Comparative Examples 1 and 2, the coating width and thickness are unstable, and the composite tape is severely scratched and the copper foil is broken. These problems seriously affect the performance and production efficiency of the battery. In Comparative Example 1, since the molten liquid is not stirred, the coating thickness is uneven, and solidified particles appear, and the final prepared composite tape has serious scratches. This is because the molten liquid is easy to form solidified particles on the surface of the copper foil without stirring. These particles will scratch the surface of the copper foil during the calendering process, resulting in scratches on the surface of the composite tape, affecting the performance and safety of the battery.

[0256] In Comparative Example 2, we can see that the copper foil of the composite tape is broken due to solidified particles during coating. This is because the heating temperature of the die head 31 is too low, resulting in incomplete solidification of the coated molten liquid, and the solidified particles will adhere to the surface of the copper foil, causing the coating layer 11 to be uneven, and the copper foil is easy to break during the calendering process, thereby affecting the performance of the battery.

[0257] It can be seen from Comparative Example 3 that, compared with the manufacturing equipment of the embodiment, when the present invention uses a die head and a die head block combination as a coating mechanism, it can be more conducive to achieving uniform coating of the molten liquid and avoiding the generation of solidified particles. When the die head 31 does not perform the coating operation, the comparative example 3 does not use the die head block 32 for covering treatment; resulting in solidified particles appearing in the composite tape during the preparation process, causing the copper foil to break, and it is impossible to successfully prepare a uniform and continuous composite tape for use. This is because when the die head block 32 is not used for covering treatment, the molten liquid is easy to solidify and block the die head outlet 317 at the die head outlet 317; and it is easy to cause air to enter, and the molten liquid is oxidized and polluted, and solidified particles are formed on the surface of the copper foil substrate 1 during the subsequent coating operation. These particles will scratch the surface of the copper foil during the calendering process, causing the composite tape to break, affecting the performance and safety of the battery. Therefore, using the die head block 32 for covering treatment is more conducive to ensuring the integrity of the composite tape.

[0258] It can also be seen from Examples 1-10 and Comparative Examples 4, 5 and 6 that the optimized preparation method of the present invention is crucial for the successful preparation of a continuous and uniform composite tape.

[0259] In comparative example 4, the molding temperature was too low during the preparation of the composite tape, and the melt splashed everywhere and could not be operated safely. As a result, the production of the composite tape could not be successfully completed. This is because the molding temperature was too low, so that the melt could not be uniformly solidified on the surface of the copper foil, resulting in the melt splashing everywhere, making it impossible to operate safely, and failing to obtain a uniform coating effect.

[0260] In the preparation process of the composite tape in Comparative Example 5, the temperature of the pressure roller 61 selected is too low compared to that in the embodiment, so it can be observed that the prepared composite tape has obvious scratches. This is because the temperature of the pressure roller 61 is improperly set, resulting in uneven solidification of the molten liquid on the surface of the copper foil, which in turn produces scratches. This uneven solidification process not only affects the surface quality of the composite tape, but also reduces the performance of the battery. Therefore, selecting a suitable temperature of the pressure roller 61 is crucial to ensure the uniformity of the coating layer 11 and the performance of the battery.

[0261] In Comparative Example 6, the copper foil was broken during the calendering process because the roll gap was set too small. This shows that during the coating process, the size of the roll gap needs to be precisely controlled to avoid unnecessary damage to the copper foil. A suitable roll gap setting can ensure the uniformity of the coating layer 11, while avoiding copper foil breakage and ensuring the smooth progress of the production process.

[0262] In comparative example 7, the conventional method of the prior art is used to directly roll and composite the substrate 1 with lithium foil to prepare a composite tape. We can observe that there are no obvious scratches on the surface of the composite tape, and the coulombic efficiency is high, but the cyclability is poor. This is because the thickness specification of lithium foil is limited. The thinnest lithium foil on the market is 5±1um thick. The main material of the negative electrode sheet of the present embodiment 1-9 and comparative example 1-6 is graphite. The amount of pre-lithium required for the graphite negative electrode is 8-10%, corresponding to a lithium layer thickness of 3±1μm. The excessive lithium supplementation in comparative example 6 causes the capacity of the prepared battery to decay rapidly during cycling.

[0263] It can be seen from Example 10 that the manufacturing equipment of the present invention is also suitable for sodium supplementation treatment of negative electrode sheets of sodium ion batteries; it shows that the equipment of the present invention can not only successfully realize pre-lithiation to prepare composite belts, but can also be used for the preparation of other metal composite belts; it has high flexibility and applicability; and has high industrial practical value.

[0264] It can be seen from Examples 1-10 and Example 11 that further heating of the substrate by the substrate heating mechanism 8 before coating is more conducive to reducing the contact angle of the lithium melt, which is conducive to further preparing a thinner coating layer, enhancing the bonding between the molten lithium and the substrate, and further improving the coulombic efficiency and cycle performance of the battery.

[0265] Fig.14 is the contact angle between the metal lithium solution and the substrate when coating the substrate in Example 1, and the contact angle is measured to be in the range of 30-60°; Fig.15The contact angle between the lithium melt and the heated substrate when the heated substrate is coated with the metallic lithium solution in Example 11 is measured to be in the range of 1-10°; this indicates that further optimization of the present invention, heating the substrate before coating can further reduce the contact angle of the metal melt, thereby being more conducive to preparing a thinner coating; and making the most of its effect on improving battery performance.

[0266] It should be noted that the above is only one of the embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite belt; characterized in that, The composite tape comprises a substrate (1) and a coating layer (11); the coating layer (11) is located on the substrate (1); the coating layer (11) is continuously arranged along the length direction of the substrate (1) and is arranged at intervals in the width direction of the substrate (1); the thickness of the coating layer (11) is selected from 0.1 to 100 μm.

2. The composite tape according to claim 1, characterized in that: The coating layer (11) preferably has a thickness of 0.1 to 5 μm; the substrate (1) is selected from one or more of metal foil, lithium battery positive electrode sheet, lithium battery negative electrode sheet, sodium battery positive electrode sheet or sodium battery negative electrode sheet; Further, the coating layer (11) is selected from a metal coating layer; Furthermore, the thickness of the coating layer (11) is preferably from 0.1 to 3 μm; Furthermore, the metal foil is selected from a metal-containing foil layer; as some specific examples: the metal-containing foil is selected from one or more of copper, aluminum, nickel, and tin; or a metal-containing foil formed by a composite of one or more non-metallic elements selected from carbon, silicon, boron, and phosphorus and one or more metal elements selected from copper, aluminum, nickel, and tin; Furthermore, the metal coating layer is a metal coating layer composed of one or more metals selected from potassium, sodium, indium, lithium, zinc, lead, silicon, and tin, or alloys thereof and conductive additives; Furthermore, the metal coating layer is preferably one or more selected from lithium and sodium; Furthermore, the conductive additive is selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, conductive polymer, and metal conductive agent; and the proportion of the conductive additive is selected from 0.01-50%.

3. A composite tape manufacturing device, characterized in that: The composite tape comprises the composite tape according to any one of claims 1 or 2; the manufacturing equipment of the composite tape comprises: A conveying system (2) for continuously conveying the substrate (1); A coating mechanism (3) comprising a die head (31), wherein the die head (31) is used to coat the continuously transported substrate (1) with a molten liquid under a protective atmosphere; A molten liquid conveying system (4) for conveying the molten liquid to the die head (31) under a protective atmosphere; A cooling and shaping mechanism (5) for cooling and shaping the coated substrate (1); A calendering mechanism (6) is used to calender the substrate (1) after cooling and shaping; The coating mechanism (3), the cooling and shaping mechanism (5), and the calendering mechanism (6) are arranged in sequence along the conveying direction of the substrate (1).

4. The manufacturing equipment of the composite tape according to claim 3, characterized in that: The die head (31) comprises an upper die head (311) and a lower die head (312); the upper die head (311) and the lower die head (312) are covered to form a hollow liquid storage tank (313); The liquid storage tank (313) has a rotatable stirring device (314) inside; Both ends of the stirring device (314) are also provided with detachable sealing devices (315); at least one of the sealing devices (315) is provided with a high-pressure protective gas inlet (3151) connected to the liquid storage tank (313); The manufacturing device may also have a substrate heating mechanism (8) for heating the substrate (1) before coating; Furthermore, the substrate heating mechanism (8) comprises an upper component (81) and a lower component (82); the upper component (81) and the lower component (82) are covered to form a hollow chamber; a plurality of groups of rollers (83) are arranged inside the chamber; Furthermore, the upper component (81) and the lower component (82) cover and contact the part thereof and are provided with a substrate inlet (84) and a substrate outlet (85) along the conveying direction of the substrate (1); Furthermore, after the upper component (81) and the lower component (82) are closed, two sides of the exterior are independently provided with a hot air inlet (86) and a hot air outlet (87); Furthermore, the substrate heating mechanism (8) is also connected to a heating box (88); the heating box (88) is connected to the hot air inlet (86) of the substrate heating mechanism (8) via a pipeline.

5. The manufacturing equipment of the composite tape according to claim 4, characterized in that: Ports (3131) capable of allowing the stirring device (314) to pass through are respectively arranged in the upper die head (311) and the lower die head (312) at the end positions of the liquid storage tank (313), and the inner wall of the port (3131) is provided with an inner wall groove (31311), and the stirring device (314) is provided with a groove (31312) matching and engaging with the inner wall groove (31311) for fixing the stirring device (314); the outer wall of the port (3131) is provided with an outer groove (31313) for fixing the sealing device (315); Furthermore, the sealing device (315) further comprises a sealing cover plate (3152) and a cover plate protrusion (3153); the sealing cover plate (3152) has a diameter larger than the cover plate protrusion (3153) and is integrated with the cover plate protrusion (3153); the cover plate protrusion (3153) is sealingly plugged into an outer groove (31313) on the outer wall of the port (3131); Furthermore, the sealing cover plate (3152) is provided with the high-pressure protective gas inlet (3151); at the same time, the port (3131) is provided with an inlet channel (3154) corresponding to the high-pressure protective gas inlet (3151), and the inlet channel (3154) is connected to the inner wall groove (31311) to realize the air intake of the liquid storage tank (313).

6. The manufacturing equipment of the composite tape according to claim 4, characterized in that: The die head (31) further comprises a gasket (316), wherein the gasket (316) is arranged in a region between the liquid storage tank (313) and the edge of the die head, and the gasket (316) is provided with a gasket opening (3161) towards the edge of the die head, and the molten liquid is evenly distributed and discharged through the gasket opening (3161); wherein, on the die head (31), the die head edge corresponding to one side of the gasket opening (3161) is the die head discharge port (317); The die head (31) further comprises a fine adjustment mechanism (318); the fine adjustment mechanism (318) is arranged on the upper die head (311); the die head (31) further comprises a die head heating device (33); Furthermore, at least two positioning pins (3162) are provided on the gasket (316), and the positioning pins (3162) are used to fix the gasket (316) on the die head (31); Furthermore, the fine-tuning mechanism (318) comprises an adjustment plate (3181) and at least two threaded screws (3182) arranged in parallel; the adjustment plate (3181) is provided with a threaded hole (3183) corresponding to the threaded screw (3182); the threaded screw (3182) is connected to the adjustment plate (3181) via the threaded hole (3183); the setting position of the adjustment plate (3181) can be relatively fixed with the position of the upper die head (311); the adjustment free end of the threaded screw (3182) acts on the upper die head (311) to change the opening size of the die head discharge port (317) by applying a force to the upper die head (311).

7. The manufacturing equipment of the composite tape according to claim 3, characterized in that: The coating mechanism (3) further comprises a die stopper (32); the die stopper (32) is movably arranged on one side of the die (31); and is used to cover the die (31) when the die (31) is not coated, so as to prevent the die (31) from leaking liquid; Furthermore, the die head stopper (32) comprises a movable bracket (321) and a baffle (322); the baffle (322) is detachably arranged on the bracket (321) and close to one side of the die head (31); Furthermore, the die block (32) further comprises a block heating device (323), and the block heating device (323) is detachably arranged on the bracket (321) and away from one side of the die (31); Furthermore, a waste liquid collection tank (324) is detachably provided below the baffle (322).

8. The manufacturing equipment of the composite tape according to claim 3, characterized in that: The molten liquid transmission system (4) comprises: a feeding and ventilation metering bin (41), a molten liquid tank (42), a molten liquid storage tank (43), and a protective gas tank (44); The conveying system (2) comprises an unwinding system (21) and a rewinding system (22); The cooling and shaping mechanism (5) is arranged behind the coating mechanism (3) along the conveying direction of the substrate (1) and is used to cool and shape the coated composite strip; the cooling and shaping mechanism (5) comprises at least one set of upper cooling rollers (51) and lower cooling rollers (52) which are arranged on the upper and lower sides of the substrate (1) and are coaxially arranged; The calendering mechanism (6) is arranged behind the cooling and shaping mechanism (5) along the conveying direction of the substrate (1), and the calendering mechanism (6) comprises at least one group of pressure rollers (61) coaxially arranged on the upper and lower sides of the substrate (1); The composite tape manufacturing device further comprises an encoding mechanism (7), wherein the encoding mechanism (7) is arranged between the calendering mechanism (6) and the winding system (22); the encoding mechanism (7) comprises at least one group of tension rollers (71) arranged coaxially on both sides of the substrate (1), and the encoding mechanism (7) further comprises an encoding rolling roller (72) and an encoder (73); Furthermore, one end of the protective gas tank (44) is independently connected to the feeding and ventilation metering bin (41), the melting tank (42), and the melt storage tank (43); and the other end is connected to the high-pressure protective gas inlet (3151) on the die head (31); Furthermore, the molten liquid transfer system (4) is also provided with a solution pump (45), and the solution pump (45) is used to feed the die head (31); Furthermore, the molten liquid transmission system (4) further comprises a delivery pipe (46) for sequentially connecting various parts of the molten liquid transmission system (4); Furthermore, the molten liquid transfer system (4) further comprises a vacuum pump (47), and the vacuum pump (47) is connected to the feeding and ventilation metering bin (41); Furthermore, the unwinding system (21) comprises an unwinding shaft (211) and at least one group of unwinding rolling rollers (212); the unwinding shaft (211) is used to sleeve the substrate (1), and the unwinding rolling rollers (212) are arranged between the unwinding shaft (211) and the coating mechanism (3) to achieve continuous supply of the substrate (1); Furthermore, the winding system (22) is arranged behind the calendering mechanism (6) along the conveying direction of the substrate (1), and comprises a winding shaft (221) and at least one group of winding rollers (222); the winding rollers (222) are arranged between the winding shaft (221) and the calendering mechanism (6).

9. A method for preparing a composite tape; characterized in that: A composite tape or a composite tape manufacturing device comprising any one of claims 1 to 8; The steps include: S1: conveying the molten liquid to the die head (31) under a protective atmosphere through the molten liquid conveying system (4); S2: The die head (31) stirs the molten liquid under a protective atmosphere and simultaneously coats the continuously transported substrate (1); S3: Cooling and shaping the coated substrate (1); S4: The cooled and shaped substrate (1) is subjected to calendering treatment to obtain a composite tape having a plurality of uniform and continuous coating layers (11).

10. The method for preparing a composite tape according to claim 9, characterized in that: When the die head (31) in S2 is not coating, a movable die head stopper (32) is used to cover the die head discharge port (317); In the above-mentioned S4, the substrate (1) may also pass through a substrate heating mechanism (8) before reaching the die outlet (317); When cooling and shaping the substrate (1) in S3, at least one set of upper cooling rollers (51) and lower cooling rollers (52) are provided on the upper and lower sides of the substrate (1), respectively; wherein the temperature of the upper cooling rollers (51) is selected from 15-150° C.; the temperature of the lower cooling rollers (52) is selected from 15-100° C.; the relationship between the roller gap distance d between each set of upper cooling rollers (51) and lower cooling rollers (52) and the total thickness D of the substrate (1) after coating by the die head (31) is d=m D, and m is selected from 0.7-1.6; Further, the heating temperature of the die block (32) is selected from 50-500°C; Furthermore, the temperature range of the die head (31) during coating is selected from 100-500°C; Furthermore, the temperature range of the substrate heating mechanism (8) is 100-350 degrees; Furthermore, the calendering treatment in S4 is achieved by at least one set of pressure rollers (61) coaxially arranged on the upper and lower sides of the substrate (1), and the relationship between the roller gap distance y between each set of pressure rollers (61) and the total thickness Y of the substrate (1) after cooling and shaping is y=nY, where n is selected from 0.5-1.3; Further, the temperature of the upper cooling roller (51) is preferably selected from 20-50°C; the temperature of the lower cooling roller (52) is selected from 20-30°C; The temperature range of the pressure roller (61) is selected from 80-200°C.

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