Die head

Abstract

The utility model provides a die head. Comprising an upper die head and a lower die head and is used for coating molten liquid on a continuously conveyed base material in a protective atmosphere; the upper die head and the lower die head are covered to form a hollow liquid storage tank; a rotatable stirring device is arranged in the liquid storage tank; detachable sealing devices are further arranged at the two ends of the stirring device; and at least one sealing device is provided with a high-pressure protective gas inlet communicated with the liquid storage tank. The lithium melting liquid is conveyed to the die head through the melting liquid 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 continuous and uniform lithium strip with the minimum thickness of 0.1 mu m can be obtained, and a more efficient and safer solution and a preparation device are provided for pre-lithiation research.

Description

Technical Field

[0001] This utility model belongs to the field of battery manufacturing technology, and specifically relates to a mold head. Background Technology

[0002] Lithium-ion batteries face a series of challenges in practical applications, with improving energy density being one of the key issues. To address this challenge, pre-lithiation has received widespread attention and research as an effective technical approach. Pre-lithiation aims to improve the initial capacity and energy density of lithium-ion batteries by pre-filling them with lithium, thereby optimizing their overall performance.

[0003] In pre-lithiation research, a common and simple method is to bond lithium metal foil to the surface of the negative electrode for pre-lithiation. This method is not only simple to operate but also has good compatibility with existing battery manufacturing processes, and is therefore considered to have broad application prospects. However, the pre-lithiation process has strict requirements on the thickness of the lithium metal foil. It is generally believed in academia and industry that the thickness of the lithium foil needs to be less than 5 micrometers to meet the requirements of pre-lithiation.

[0004] However, the thickness of commercially rolled lithium foil is currently often no less than 50 micrometers, far exceeding the thickness requirements of pre-lithiation processes. Although rolling is a common method for preparing metal foils, lithium metal has extremely poor processing properties, low tensile strength, poor ductility, and is soft and easily deformed, making it difficult to further reduce the thickness of lithium foil through rolling. Under external forces, pores or cracks are easily generated inside and at the boundaries of lithium metal, which not only reduces the actual strength of the lithium foil but also increases the difficulty and complexity of the processing.

[0005] Furthermore, lithium is chemically extremely reactive, readily reacting with oxygen and moisture in the atmosphere, leading to atmospheric corrosion. Corrosion products such as lithium oxide, lithium hydroxide, and lithium carbonate have porous structures, failing to effectively protect the underlying metallic lithium. This not only further degrades the performance of the lithium foil but also negatively impacts the effectiveness of the pre-lithiation process.

[0006] Therefore, how to maintain the performance of lithium foil while achieving continuous and uniform coating and preparing composite strips that meet the requirements of pre-lithiation has become a difficult point and an urgent problem to be solved in the current technological development. Utility Model Content

[0007] This utility model addresses the problems in the prior art by disclosing a die head. This die head discharges material through shims with adjustable thickness, width, and number of openings under a protective atmosphere; simultaneously, the die head also contains a stirring device, providing a good operating environment and apparatus for obtaining continuous, uniform, and thickness-adjustable lithium strips.

[0008] This utility model is achieved through the following technical solution:

[0009] In the first aspect, the present invention provides a mold head, which has two parts: an upper mold head and a lower mold head; the upper mold head and the lower mold head are combined to form a hollow liquid storage tank;

[0010] The storage tank has a rotatable stirring device inside;

[0011] The stirring device is also provided with detachable sealing devices at both ends; at least one of the sealing devices is provided with a high-pressure protective gas inlet that communicates with the liquid storage tank.

[0012] As a further embodiment, the stirring device includes a stirring rod and a stirring shaft for driving the stirring rod to rotate; the stirring rod is housed inside the liquid storage tank.

[0013] As a further embodiment, the upper mold head and the lower mold head are respectively provided with ports at the end positions of the liquid storage tank, 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 that matches and fits into 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.

[0014] As a further embodiment, the sealing device also includes a sealing cover plate and a cover plate protrusion. The diameter of the sealing cover plate is larger than that of the cover plate protrusion, and the sealing cover plate is integrally formed with the cover plate protrusion. The cover plate protrusion is sealed and inserted into the outer groove of the outer wall of the port.

[0015] As a further embodiment, the sealing cover plate is provided with a high-pressure protective gas inlet; at the same time, the port is provided with an air intake channel corresponding to the high-pressure protective gas inlet, and the air intake channel is connected to the inner wall groove to realize the air intake of the liquid storage tank.

[0016] As a further embodiment, the die head also includes a gasket, which is disposed in the area between the liquid storage tank and the edge of the die head. The gasket has an opening facing the edge of the die head, and the molten liquid is evenly distributed and discharged through the gasket opening. The edge of the die head corresponding to one side of the gasket opening is the die head discharge port.

[0017] As a further solution, the gasket is provided with at least two locating pins, which are used to fix the gasket on the mold head.

[0018] As a further embodiment, the mold head also includes a fine-tuning mechanism; the fine-tuning mechanism is disposed on the upper mold head; the mold head also has a mold head heating device.

[0019] As a further embodiment, the fine-tuning mechanism includes an adjusting plate and at least two threaded screws arranged in parallel; the adjusting plate is provided with threaded holes corresponding to the threaded screws, the threaded screws are connected to the adjusting plate through the threaded holes, the setting position of the adjusting plate can be fixed relative to the position of the upper die head, and the free end of the threaded screws acts on the upper die head to change the opening size of the die head outlet by applying a force to the upper die head.

[0020] The features and beneficial effects of this utility model are as follows:

[0021] In this invention, the molten liquid supplied to the die head is always surrounded by a protective atmosphere; this effectively prevents the molten liquid from oxidizing upon contact with air during transport, thus maintaining the purity and chemical stability of the molten liquid. Furthermore, the use of a protective atmosphere helps reduce the evaporation loss of the molten liquid at high temperatures, ensuring the quality and uniformity of the coating layer. It also improves the adhesion between the coating layer and the substrate during the coating process.

[0022] The die head of this invention, under the combined action of a protective atmosphere and a stirring device, coats a continuously conveyed substrate. This prevents edge solidification of the molten liquid and avoids oxidative contamination, achieving continuous and uniform coating of the substrate surface. This effectively avoids the problems of uneven lithium powder dispersion and discontinuous lithium foil rolling and lamination in traditional pre-lithiation methods. Simultaneously, the die head of this invention has a heating device to ensure that the molten metal material maintains appropriate fluidity during the coating process.

[0023] This invention's die head also features a gasket opening for molten liquid coating. By adjusting the thickness, width, and number of gasket openings, multiple continuous and uniform coating layers can be simultaneously applied to the composite strip, and the thickness and width of the coating layers are adjustable. Furthermore, the die head includes a fine-tuning mechanism to precisely control the coating layer thickness, ensuring the stability and repeatability of the coating quality. This provides a new solution for pre-lithiation technology in lithium-ion and sodium-ion batteries. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the molten liquid transfer system in embodiments 1-11 of this utility model;

[0026] Figure 2This is a schematic diagram of the manufacturing equipment for the composite belt in embodiments 1-10 of this utility model;

[0027] Figure 3 This is a schematic diagram of the structure of the mold head in embodiments 1-11 of this utility model;

[0028] Figure 4 This is a partial structural schematic diagram of the fine-tuning structure in embodiments 1-11 of this utility model;

[0029] Figure 5 This is a partial structural diagram of the mold head in embodiments 1-11 of this utility model;

[0030] Figure 6 This is a partial structural diagram of the mold head in embodiments 1-11 of this utility model;

[0031] Figure 7 This is a schematic diagram of the structure of the die head stop block in embodiments 1-11 of this utility model;

[0032] Figure 8 This is a schematic diagram of the gasket structure in embodiments 1-11 of this utility model;

[0033] Figure 9 This is a schematic diagram of the composite strip in embodiments 1-11 of this utility model;

[0034] Figure 10 This is a partial structural diagram of the mold head in embodiments 1-11 of this utility model;

[0035] Figure 11 This is a schematic diagram of the manufacturing equipment for the composite belt in Embodiment 11 of this utility model;

[0036] Figure 12 This is a schematic diagram of the substrate heating mechanism in Embodiment 11 of this utility model;

[0037] Figure 13 This is a partial structural schematic diagram of the substrate heating mechanism in Embodiment 11 of this utility model.

[0038] Figure label:

[0039] Substrate 1; Coating layer 11;

[0040] Conveying system 2; Unwinding system 21; Rewinding system 22; Unwinding shaft 211; Unwinding roller 212; Rewinding shaft 221; Rewinding roller 222;

[0041] 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 head outlet 317; Positioning pin 3162; Fine adjustment mechanism 318; Adjusting plate 3181; Threaded screw 3182; Threaded hole 3183; Fixing device 319; Die head heating device 33; Die head stop 32; Bracket 321; Baffle 322; Baffle heating device 323; Waste liquid collection tank 324; Die head inlet 331; Die head return outlet 332;

[0042] 4. Molten liquid transfer system; 41. Feeding and aeration metering chamber; 42. Molten tank; 43. Molten liquid storage tank; 44. Protective gas tank; 45. Solution pump; 46. Delivery pipe; 47. Vacuum pump;

[0043] Cooling and shaping mechanism 5; upper cooling roller 51; lower cooling roller 52;

[0044] Calendering mechanism 6; pressing roller 61;

[0045] Encoding mechanism 7; tension roller 71; encoding roller 72; encoder 73;

[0046] 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 Implementation

[0047] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be provided below, along with embodiments of this utility model, but this does not limit the scope of this utility model.

[0048] In the description of this utility model, it should be noted that the terms "center," "middle," "upper," "lower," "left," "right," "inner," "outer," "top," "bottom," "side," "vertical," and "horizontal," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] Generally, materials requiring coating with molten metal are collectively referred to as substrates. This invention has researched new pre-lithiation technology to address issues such as excessive lithium, discontinuous lithium layers, and uneven pre-lithiation that easily occur when using lithium powder or lithium metal composite strips to prepare composite strips on substrates requiring pre-lithiation. This invention has found that coating substrates with molten liquid is more convenient and controllable, potentially alleviating the problems of discontinuous or uneven pre-lithiation. However, as a fluid, the fluidity, uniformity, and susceptibility to oxidation of molten liquid when coating substrates are key areas that researchers need to explore. Based on this, this invention presents a new pre-lithiation technology, proposing a composite strip preparation device and manufacturing method, aiming to produce composite strips with multiple continuous and uniform lithium layers simultaneously.

[0050] Reference Figure 1-13 In a first aspect, the present invention provides a composite tape; the composite tape includes a substrate 1 and a coating layer 11; the coating layer 11 is located on the substrate 1; the coating layer 11 is continuously disposed along the length direction of the substrate 1 and spaced apart in the width direction of the substrate 1; the thickness of the coating layer 11 is selected from 0.1 to 100 μm.

[0051] Specifically, the spacing of the coating layer 11 is consistent with the distance between every two gasket openings 3161 of the die head 31 gasket 316, and the thickness of the coating layer 11 is consistent with the thickness of each gasket opening 3161.

[0052] The composite tape prepared by this 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 between the coating layers 11 can be adjusted as needed. Furthermore, the composite tape provided by this invention achieves continuity and uniformity while having a minimum thickness of 0.1 μm, and the thickness is adjustable, facilitating customization according to requirements; thus significantly reducing the amount of metal used while ensuring battery performance and safety. For example, when using graphite anodes, anodes with low silicon and carbon content, or thinner anode sheets, only 1-2 μm of lithium replenishment is needed. However, the current market's composite strip rolling process, which mainly uses lithium strips, can only achieve a thickness of around 5 μm. When rolling to prepare even thinner thicknesses, it is difficult to roll thinner lithium strips due to the high ductility and softness of lithium metal, which easily leads to breakage. In contrast, the coating layer prepared by this invention, taking lithium and its alloys or conductive agent composite layers as an example, can have different thicknesses such as 3 μm, 7 μm, 14 μm, or 17 μm. Furthermore, thinner coatings such as 0.1 μm and 2 μm can be prepared by adjusting the equipment. This provides a more efficient and safer solution to the problems of excessive, discontinuous, and uneven lithium layer coating in existing technologies, which require multiple dicing of the negative electrode sheet for pre-lithiation. Through the composite strip of this invention, uniform pre-lithiation of the battery negative electrode material can be achieved, thereby improving the battery's initial coulombic efficiency, reducing irreversible lithium loss, enhancing the battery's cycle stability, and extending its service life. At the same time, it can flexibly adapt to the needs of different battery designs, providing greater design space for battery manufacturing.

[0053] As some specific options, the thickness of the coating layer 11 is preferably from 0.1 to 5 μm;

[0054] Furthermore, the thickness of the coating layer 11 is preferably between 0.1 and 3 μm.

[0055] This invention does not impose any particular restrictions on the material of the substrate 1. When performing battery pre-lithiation, the substrate 1 is selected from one or more of the following: metal foil, lithium battery positive electrode sheet, lithium battery negative electrode sheet, sodium battery positive electrode sheet, or sodium battery negative electrode sheet.

[0056] Furthermore, the metal foil is selected from metal foils; as some specific examples: the metal foil is selected from one or more metal foils selected from copper, aluminum, nickel, and tin; or it is selected from one or more non-metallic elements selected from carbon, silicon, boron, and phosphorus combined with one or more metallic elements selected from copper, aluminum, nickel, and tin to form a metal foil.

[0057] Taking the pre-lithiation preparation of lithium composite strips as an example; after using the device of this invention to coat the substrate with molten lithium, on the one hand, the composite strip prepared by coating the substrate with molten lithium can be directly coated with active materials to prepare battery electrodes for use; on the other hand, the substrate can also be used as a transfer strip; after coating the substrate with molten lithium to prepare the composite strip, the lithium strip on the composite strip can be transferred separately and transferred to the electrode through calendering or other methods. The substrate can be reused for coating and transferring molten lithium.

[0058] As some specific options, the coating layer 11 is selected from metal coating layers.

[0059] Furthermore, the metal coating layer is selected from one or more metals or their alloys selected from potassium, sodium, indium, lithium, zinc, lead, silicon, and tin, and is composed of a metal coating layer with conductive additives; for lithium batteries that require pre-lithiation, the coating layer 11 of the composite strip is made of molten lithium metal.

[0060] Furthermore, the conductive additives are selected from one or more of carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, conductive polymers, and metal conductive agents; the proportion of conductive additives is selected from 0.01-50%.

[0061] As some specific options, the metal coating is preferably made from one or more metals selected from lithium and sodium.

[0062] In the preparation process of the composite tape of this utility model, in order to further improve the bonding strength between the coating layer and the substrate and avoid oxidation of the molten metal, an additive can be added to the surface of the molten metal or the substrate. The additive may include metal antioxidants or fluxes. The metal antioxidants may be selected from phosphates (such as sodium dihydrogen phosphate, sodium phosphite, sodium citrate, etc.), silicates (such as sodium silicate, calcium silicate, etc.), borates (such as potassium borate, sodium borate, etc.), and organometallic antioxidants (such as organotin, organocobalt, etc.). The flux may be selected from one or more of organic solvents, rosin resin and its derivatives.

[0063] The manufacturing equipment of this invention is particularly suitable for the preparation of lithium composite strips and sodium composite strips. Molten lithium and molten sodium metals exhibit severe beading during preparation, resulting in high surface tension and easy oxidation. This invention's equipment effectively solves these problems by incorporating a stirring device and protective gas inside the die, along with die head baffles, cooling, and extension structures. The stirring device inside the die ensures uniform distribution of the molten metal and prevents beading; the protective gas effectively isolates the metal from air, reducing oxidation; the die head baffle helps control the flow direction of the molten metal and the thickness of the coating layer; and the cooling and extension structures ensure uniform shrinkage of the coating layer during cooling, preventing crack formation. Through this optimized combination of structures, the equipment of this invention can produce composite strips with uniform thickness and good adhesion, meeting the stringent requirements for pre-lithiation layers in battery manufacturing.

[0064] Secondly, this utility model provides a composite tape manufacturing equipment, including the composite tape described in the first aspect;

[0065] The manufacturing equipment includes:

[0066] Conveying system 2 is used for continuous conveying of substrate 1;

[0067] The coating mechanism 3 includes a die head 31, which is used to coat a continuously conveyed substrate 1 with molten liquid under a protective atmosphere;

[0068] The molten liquid transfer system 4 is used to deliver molten liquid to the die head 31 under a protective atmosphere;

[0069] The cooling and shaping mechanism 5 is used to cool and shape the coated substrate 1.

[0070] The calendering mechanism 6 is used to calender the substrate 1 after it has been cooled and shaped.

[0071] The coating mechanism 3, cooling and shaping mechanism 5, and calendering mechanism 6 are arranged sequentially along the conveying direction of the substrate 1.

[0072] Through the coordinated work of the above mechanisms, the coating of substrate 1 was achieved.

[0073] As some specific solutions, the mold head 31 has two parts: an upper mold head 311 and a lower mold head 312; the upper mold head 311 and the lower mold head 312 are closed to form a hollow liquid storage tank 313 for storing molten liquid;

[0074] The storage tank 313 has a rotatable stirring device 314 inside for stirring the molten liquid;

[0075] The stirring device 314 is also provided with detachable sealing devices 315 at both ends; used to seal the liquid storage tank 313 when the mold head 31 is closed, to prevent the molten liquid in the liquid storage tank 313 from leaking and oxidizing, thus affecting the preparation of the composite belt.

[0076] At least one of the sealing devices 315 is provided with a high-pressure protective gas inlet 3151 that communicates with the liquid storage tank 313; used to introduce protective gas into the mold head 31 to ensure that the molten liquid in the liquid storage tank 313 is always coated by feeding and discharging the mold head 31 under a protective atmosphere; to prevent oxidation and contamination of the molten liquid, and to achieve uniform and continuous coating of the molten liquid to prepare the composite belt.

[0077] As some specific solutions, 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 housed inside the liquid storage tank 313 and is used to stir the molten liquid to prevent the molten liquid from producing sedimentation, edge solidification or unevenness during the coating process, thereby ensuring the continuity and consistency of the coating layer 11.

[0078] 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 achieved through an external transmission device 3143. This utility model 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 in principle. Those skilled in the art can choose a suitable connection method as needed; for example, the stirring rod 3141 and the stirring shaft 3142 can be connected by thread, welding, keying, or other mechanical methods; the transmission device 3143 that achieves the rotation of the stirring device 314 can be set inside or outside the stirring device 314, or at a suitable location.

[0079] The width and length of the stirring rod 3141 are not limited in principle, but it is preferable that it can basically cover the entire space of the storage tank 313, while avoiding direct contact between the stirring rod 3141 and the wall of the storage tank 313. This reduces wear on the wall of the storage tank 313 during stirring while ensuring comprehensive stirring effect. Those skilled in the art can choose appropriate length and width designs according to actual needs. For example, the width and length of the stirring rod 3141 can each be designed to occupy 60%-95% of the diameter and length of the storage tank 313 space, respectively.

[0080] As some specific solutions, the shape of the stirring rod 3141 is not limited, and the exemplary shape can be selected from one or more of the following: rectangle, square, circle, and ellipse.

[0081] As some specific solutions, the upper mold head 311 and the lower mold head 312 are respectively provided with ports 3131 at the ends of the liquid storage tank 313, allowing the stirring device 314 to pass through. The inner wall of the port 3131 is provided with an inner wall groove 31311, and the stirring device 314 is provided with a channel 31312 that matches and fits into 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 for fixing the sealing device 315 to achieve sealing of the mold head 31.

[0082] As some specific solutions, the sealing device 315 also includes a sealing cover plate 3152 and a cover plate protrusion 3153. The diameter of the sealing cover plate 3152 is larger than that of the cover plate protrusion 3153, and it is integrally set with the cover plate protrusion 3153. The cover plate protrusion 3153 is sealed and inserted into the outer groove 31313 on the outer wall of the port 3131. This achieves a mechanical seal on the liquid storage tank 313, preventing leakage, solidification and blockage of the liquid storage tank 313, and oxidation of the molten liquid caused by air infiltration. This facilitates the continuous and uniform coating of the substrate 1 by the die head 31 to prepare the composite tape.

[0083] As some specific solutions, 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 air intake channel 3154 corresponding to the high-pressure protective gas inlet 3151, and the air intake channel 3154 is connected to the inner wall groove 31311 to realize the air intake of the liquid storage tank 313.

[0084] As some specific solutions, the die head 31 also includes a gasket 316, which is disposed in the area between the liquid storage tank 313 and the edge of the die head. The gasket 316 has a gasket opening 3161 facing the edge of the die head, and the molten liquid is evenly distributed and discharged through the gasket opening 3161. On the die head 31, the edge of the die head corresponding to one side of the gasket opening 3161 is the die head discharge port 317.

[0085] As some specific solutions, 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 number, thickness, and width of the gasket openings 3161 can be adjusted to prepare coating layers 11 with different numbers, thicknesses, and widths on the substrate 1, thereby obtaining a composite tape with multiple continuous and uniform coating layers 11.

[0086] As some specific solutions, the gasket 316 is provided with at least two positioning pins 3162, which are used to fix the gasket 316 on the mold head 31.

[0087] In principle, this invention does not limit the number, width, and length of the gasket openings 3161. Those skilled in the art can make corresponding settings according to different coating layer 11 thicknesses, the number of parallel strips on the substrate 1, and the width; thereby achieving continuous and uniform coating on the substrate 1, and thus preparing a composite strip with multiple coating layers 11.

[0088] 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 such as straight line, wavy, and arc to adapt to different coating requirements and effects.

[0089] As a specific embodiment, the die head 31 also includes a fine-tuning mechanism 318. The fine-tuning mechanism 318 is disposed on the upper die head 311, specifically above the die head outlet 317. The size of the die head outlet 317 is fine-tuned by the fine-tuning mechanism 318 to adapt to the coating requirements of substrates 1 and molten liquids of different thicknesses, thus preparing a uniform and continuous composite strip. The design of the fine-tuning mechanism 318 allows the operator to precisely control the thickness of the coating layer 11, thereby achieving precise control of the lithium layer thickness of the composite strip. Furthermore, the addition of the fine-tuning mechanism 318 improves the flexibility and applicability of the equipment, enabling it to adapt to different production requirements.

[0090] As some specific solutions, the fine-tuning mechanism 318 includes an adjusting plate 3181 and at least two threaded screws 3182 arranged in parallel. The adjusting plate 3181 is provided with threaded holes 3183 corresponding to the threaded screws 3182. The threaded screws 3182 are connected to the adjusting plate 3181 through the threaded holes 3183. The setting position of the adjusting plate 3181 can be fixed relative to the position of the upper die head 311. The free end of the threaded screw 3182 acts on the upper die head 311 to change the opening size of the die head outlet 317 by applying a force to the upper die head 311, so as to adapt to the coating requirements of substrates 1 and molten liquid of different thicknesses.

[0091] Furthermore, the adjusting plate 3181 can be relatively fixed to the upper mold head 311 by an external fixing device 319. This invention does not limit the device used to fix the adjusting plate 3181 in principle; those skilled in the art can select a suitable fixing device 319 and its setting position as needed.

[0092] As some specific solutions, the mold head 31 also has a mold head heating device 33; the mold head heating device 33 is used to provide temperature to the mold head 31 to prevent the molten liquid from solidifying.

[0093] This invention does not limit the specific location, method, or number of the mold head heating device 33; those skilled in the art can select and design it according to actual needs. Preferably, the mold head heating device 33 is housed within a hollow cavity inside the mold head 31. For example, one heating device can be installed in each of the upper mold head 311 and the lower mold head 312, ensuring uniform temperature of the mold head 31, further improving the uniformity and quality of the coating, and preventing the molten liquid from solidifying. The heating devices of the upper mold head 311 and the lower mold head 312 can be independently controlled to adapt to the heating requirements of different molten liquids.

[0094] The die head 31 of this utility model also includes a die head inlet 331 and a die head return outlet 332; the melt transfer system 4 connects the die head inlet 331 and the die head return outlet 332, realizing the feeding of the die head 31 during coating and the return of the melt in the die head 31 to the melt storage tank 43 when coating stops, thus realizing the circulation of the melt in the transfer system. This utility model does not limit the specific location of the die head inlet 331 and the die head return outlet 332 in principle; those skilled in the art can select and design according to actual needs; as some examples, the die head inlet 331 can be located on one side of the upper die head 311, and the die head return outlet 332 can be located on one side of the lower die head 312.

[0095] As some specific solutions, the coating mechanism 3 also includes a mold head stop 32; the mold head stop 32 is movably disposed on one side of the mold head, and is used to cover the mold head 31 when the mold head 31 is not coated, so as to prevent the mold head 31 from leaking liquid.

[0096] As some specific solutions, the die head block 32 includes a movable bracket 321 and a baffle 322; the baffle 322 is detachably mounted on the bracket 321 and close to the die head 31, and is used to cover the discharge side of the die head 31 to prevent leakage, oxidation and solidification blockage.

[0097] This utility model movably mounts the bracket 321 on the fixing device 319, and the bracket 321 can be moved by adjusting the fixing device 319. This utility model does not limit the way or position of the bracket 321 moving. Those skilled in the art can make different choices for the position of the bracket 321 and the fixing device 319 according to actual needs.

[0098] As some specific solutions, the die head block 32 also includes a block heating device 323, which is detachably mounted on the bracket 321 and away from the die head 31; it is used to provide heating temperature, maintain the fluidity of the molten liquid, and prevent the molten liquid from solidifying.

[0099] As one specific embodiment, the die head stop 32 is movably disposed on one side of the die head outlet 317 of the die head 31.

[0100] As a specific embodiment, a waste liquid collection tank 324 can be detachably installed below the baffle 322 to collect excess molten liquid.

[0101] As some specific solutions, the molten liquid transfer system 4 includes: a feeding and ventilation metering chamber 41, a molten 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 chamber 41, the molten tank 42, and the molten liquid storage tank 43 to protect the molten liquid and prevent oxidation; the other end is connected to the high-pressure protective gas inlet 3151 on the die head 31 to protect the molten liquid inside the die head 31.

[0102] The feeding and ventilation metering chamber 41 is used to add materials under the protection of protective gas;

[0103] The melting tank 42 is used to receive materials from the feeding and ventilation chamber for melting under the action of protective gas;

[0104] The molten liquid storage tank 313 is responsible for receiving molten liquid from the molten tank 42 under the action of protective gas, and conveying molten liquid to the die head 31 to achieve continuous liquid feeding of the die head 31 to coat the substrate 1 and prepare a composite belt with a uniform and continuous coating layer 11.

[0105] As a specific embodiment, the melt transfer system 4 is also equipped with a solution pump 45, which is used to feed the die head 31.

[0106] As a specific embodiment, the molten liquid transfer system 4 also includes a conveying pipe 46, which is used to sequentially connect the various parts of the molten liquid transfer system 4 to achieve smooth molten liquid transfer.

[0107] As a specific embodiment, the molten liquid transfer system 4 also includes a vacuum pump 47, which is connected to the feeding and aeration metering chamber 41 to ensure stable pressure within the chamber and prevent air from entering the system and causing oxidation of the molten liquid. The vacuum pump 47, together with the delivery pipe 46, ensures that the entire molten liquid transfer system 4 is fully covered with protective gas.

[0108] The protective gas covering the entire interior of the molten liquid transfer system 4 and the die head 31 effectively prevents the molten liquid from oxidizing due to contact with air during transport, 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 interior of the die head 31 helps solve the problems of oxidation, corrosion, and high-precision coating of the molten metal; simultaneously, the introduction of protective gas into the die head 31 also acts as a protective gas seal, effectively ensuring that the entire molten liquid transfer mechanism is in a protective gas environment; this is beneficial for ensuring good adhesion between the coating layer 11 and the substrate 1 during coating. Furthermore, the use of protective gas can reduce the evaporation loss of the molten liquid during the coating process, further improving material utilization.

[0109] As some specific embodiments, the manufacturing equipment may also have a substrate heating mechanism 8 for heating the substrate 1 before coating; this is beneficial for improving the wettability of molten lithium and enhancing the bonding between molten lithium and the substrate 1.

[0110] 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 number 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 heated evenly during the heating process.

[0111] Furthermore, the upper component 81 and the lower component 82 are provided with a substrate inlet 84 and a substrate outlet 85 along the conveying direction of the substrate 1 at the contact portion of the cover; this is used to enable the substrate 1 to enter the substrate heating mechanism 8 for heating.

[0112] Furthermore, after the upper component 81 and the lower component 82 are closed, each of the outer sides is independently provided with a hot air inlet 86 and a hot air outlet 87;

[0113] In principle, the specific locations of the hot air inlet 86 and the hot air outlet 87 are not limited in this utility model; those skilled in the art can make selections and designs 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.

[0114] Furthermore, the substrate heating mechanism 8 is also connected to a heating box 88; the heating box 88 is connected to the hot gas inlet 86 of the substrate heating mechanism 8 via a pipe. The gas is heated by the heating box 88 and then enters the substrate heating mechanism 8 to heat the substrate 1.

[0115] This invention does not limit the specific location of the heating box, and those skilled in the art can select and design it according to actual needs; as some examples, this invention connects the heating box 88 to the outside of the substrate heating mechanism 8 to realize the heating of the substrate 1.

[0116] This invention further optimizes the equipment and process for lithium-based coatings. Before coating the substrate with molten lithium, the substrate is further heated. When the molten lithium is coated on the heated substrate, the contact angle of the molten lithium is reduced, thereby strengthening the adhesion between the coating and the substrate. Then, through subsequent cooling, shaping, and stretching treatments, the coating achieves a thinner thickness while being more uniform and smooth, and helps to eliminate scratches, resulting in better preparation results.

[0117] 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, the continuous conveying of the substrate 1 is realized.

[0118] Furthermore, the unwinding system 21 includes an unwinding shaft 211 and at least one set of unwinding rollers 212; the unwinding shaft 211 is used to sleeve the substrate 1, and the unwinding rollers 212 are arranged between the unwinding shaft 211 and the coating mechanism 3 to realize the continuous supply of the substrate 1; at the same time, it maintains the uniform tension of the substrate 1, ensures that the substrate 1 runs smoothly during the coating process, avoids loosening or breakage, and thus ensures the flatness and quality of the coating layer 11.

[0119] Furthermore, the winding system 22 is located 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 set of winding rollers 222. The winding shaft 221 is used to wind up the substrate 1, and the winding rollers 222 are located between the winding shaft 221 and the calendering mechanism 6 to maintain uniform tension of the composite tape during the winding process, ensuring that the wound composite tape is flat and wrinkle-free.

[0120] As a specific embodiment, the cooling and shaping mechanism 5 is located 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 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 stability of the shape and size of the coating.

[0121] As a specific embodiment, the calendering mechanism 6 is located behind the cooling and shaping mechanism 5 along the conveying direction of the substrate 1, and is used to further calender the coated and cooled substrate 1 to improve the smoothness and adhesion of the coating. The calendering mechanism 6 includes at least one set of spreading rollers 61 arranged coaxially on the upper and lower sides of the substrate 1. These spreading rollers 61 can be independently adjusted to adapt to composite belts of different thicknesses and materials. By precisely controlling the pressure and speed of the spreading rollers 61, scratches on the surface of the coated substrate 1 can be further eliminated, and a composite belt with multiple continuous and uniform coating layers 11 can be prepared.

[0122] As some specific embodiments, the manufacturing equipment for the composite tape also includes an encoding mechanism 7, which is disposed between the calendering mechanism 6 and the winding system 22, and is used to encode the composite tape. The encoding mechanism 7 includes at least one set of tension rollers 71 coaxially disposed on both sides of the substrate 1, which is used to further ensure the flatness of the substrate 1 and the stability and accuracy of the encoding process. The encoding mechanism 7 also includes an encoding rolling roller 72 and an encoder 73, which are used to realize the continuous rolling and encoding of the substrate 1.

[0123] Thirdly, this utility model provides a method for preparing a composite tape; comprising the composite tape described in the first aspect and the manufacturing equipment for the composite tape described in the second aspect; the steps include:

[0124] S1: Under a protective atmosphere, the raw material with metal coating is added to the feeding and gas metering chamber 41. The feeding and gas metering chamber 41 is vacuumed by the vacuum pump 47 to ensure that the raw material is fed in an oxygen-free environment.

[0125] S2: The material enters the melting tank 42 through the conveying pipe 46 from the feeding and ventilation metering chamber 41. The melted liquid after melting under the protective atmosphere passes through the melt storage tank 43 and the solution pump 45 and is then conveyed to the die head 31 through the conveying pipe 46.

[0126] S3: Under a protective atmosphere, the molten liquid is heated and stirred by the heating device and stirring device 314 inside the mold head 31;

[0127] S4: The substrate 1 is supplied through the unwinding system 21 and reaches below the die head outlet 317; the melted liquid coats the substrate 1; when coating stops, a die head stop 32 is placed on one side of the die head outlet 317.

[0128] S5: The coated substrate 1 is rapidly cooled and shaped using the cooling and shaping mechanism 5; the cooled and shaped substrate 1 is further calendered using the calendering mechanism 6; the substrate 1 is coded using the coding device; the calendered substrate 1 is wound up using the winding system 22; and finally, a composite tape with a coating layer 11 is obtained.

[0129] The preparation method of this invention employs a continuous production process, which enables continuous coating of the substrate, ensuring the uniformity and quality stability of the coating layer. Simultaneously, by controlling the die heating temperature, cooling temperature, calendering temperature, and roll gap during continuous coating, consistent physical and mechanical properties are ensured after uniform coating of the substrate. Optimized process parameters effectively reduce the scrap rate, improve production efficiency, and lower production costs. Furthermore, in the preparation method of this invention, the entire production process is carried out in a protective atmosphere, effectively preventing oxidation caused by contact between the molten liquid and air, thus guaranteeing the quality of the prepared composite tape.

[0130] As some specific solutions, in S4, the substrate 1 can also pass through the substrate heating mechanism 8 before reaching the die head outlet 317; specifically, the substrate is coated sequentially through the unwinding mechanism 21, the substrate heating mechanism 8, and the die head outlet 317.

[0131] Furthermore, the temperature range of the substrate heating mechanism 8 is 100-350 degrees Celsius.

[0132] As some specific solutions, in S2, when the die head 31 is not being coated, a movable die head stop 32 is used to cover the die head outlet 317 to prevent leakage, solidification blockage, and molten liquid oxidation contamination.

[0133] Furthermore, the heating temperature of the mold head stop 32 is selected from 50-500℃.

[0134] The temperature range of the die head stop block is beneficial for preventing leakage and solidification when the die head is covered before coating, and prevents die head blockage or the generation of solidified particles due to excessively low temperature, thus affecting the uniformity of composite tape preparation.

[0135] As some specific embodiments, the temperature range of the die 31 during coating is selected from 100-500℃. Choosing a suitable die temperature facilitates uniform coating of the molten liquid, ensuring consistent coating thickness on the substrate surface, thereby achieving good physical and mechanical properties. Furthermore, a suitable die temperature helps the molten liquid exhibit good fluidity and spreadability during the coating process, further improving the quality of the composite tape preparation.

[0136] As some specific solutions, when cooling and shaping the substrate 1 in S3, at least one set of upper cooling rollers 51 and lower cooling rollers 52 are respectively provided on the upper and lower sides of the substrate 1; wherein, the temperature of the upper cooling rollers 51 is selected from 15-150℃; the temperature of the lower cooling rollers 52 is selected from 15-100℃; 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 11 after the die head 31 is coated is d=mD, where m is selected from 0.7-1.6.

[0137] Furthermore, the temperature of the upper cooling roller 51 is preferably between 20-50°C; the temperature of the lower cooling roller 52 is selected from 20°C-30°C.

[0138] A suitable range of cooling roller temperatures and roller gap spacing facilitates rapid cooling and setting of the molten liquid on the coated substrate, reducing energy consumption during production. Furthermore, the high surface tension of the molten liquid makes it prone to beading, and rapid cooling and setting helps prevent uneven coating. Precise control of the cooling roller temperature and roller gap distance can also effectively prevent substrate deformation or excessive internal stress in the coating caused by excessively fast or slow cooling rates. In addition, reasonable temperature and gap settings ensure that the composite belt maintains appropriate tension during cooling, thereby improving product flatness and dimensional stability.

[0139] As some specific solutions, the calendering process in S4 is achieved by at least one set of pressing rollers 61 coaxially arranged on the upper and lower sides of the substrate 1. The relationship between the roller gap distance y between each set of pressing 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.

[0140] The temperature range of the pressing roller is selected from 80-200℃.

[0141] Selecting appropriate ranges for calender roll temperature and roll gap can effectively eliminate stress concentration during the cooling and shaping process, preventing internal cracks or fractures in the material; at the same time, it can further eliminate surface scratches on the composite belt, ensuring a uniform coating layer.

[0142] As some specific solutions, S4 and S5 also include an encoding operation for encoding the substrate 1.

[0143] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0144] Example 1

[0145] Copper foil (thickness: 6μm) 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 and aeration metering chamber 41, and vacuum aeration is performed by vacuum pump 47. The lithium metal enters the melting tank 42 (temperature: 280 degrees) and the molten liquid storage tank 43 (temperature: 280 degrees) in sequence through the conveying pipe 46. Then it is transported to the die head 31 by solution pump 45.

[0146] Under the protection of protective gas, the molten liquid is heated (temperature: 280 degrees) and stirred (speed: 5 r / min) by the heating device and stirring device 314 in the die head 31; the die head outlet 317 is covered by the die head baffle 32 (temperature: 200 degrees); the copper foil is continuously supplied through the unwinding system 21, and when the copper foil reaches below the die head outlet 317, the die head baffle 322 is moved and removed to coat the copper foil with molten lithium metal.

[0147] 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 (temperature of cooling roller 51 above substrate 1: 50 degrees; temperature of cooling roller 51 below substrate 1: 30 degrees; gap between rollers of each set of cooling rollers 51 (9μm).

[0148] Subsequently, the cooled and shaped substrate 1 is calendered by the calendering mechanism 6 (temperature of the pressing rollers 61 above and below the substrate 1: 130 degrees; gap of each set of pressing rollers 61: 7.5μm; pressure of each set of pressing rollers 61: 0.5 tons).

[0149] Then, the calendered substrate 1 is encoded by the encoding mechanism 7.

[0150] Finally, the composite tape is wound up by the winding system 22 to complete the preparation of the composite tape with the lithium layer.

[0151] Example 2

[0152] The specific operating method and conditions are the same as in Example 1; the difference is that the heating temperature of the mold head 31 is 320 degrees.

[0153] Example 3

[0154] The specific operating methods and conditions are the same as 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.

[0155] Example 4

[0156] The specific operation method and conditions are the same as 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 10μm.

[0157] Example 5

[0158] The specific operating methods and conditions are the same as 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 from 150 degrees.

[0159] Example 6

[0160] The specific operating methods and conditions are the same as 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 from 115 degrees.

[0161] Example 7

[0162] The specific operation method and conditions are the same as in Example 1; the difference is that during the calendering process, the gap between the rollers 61 of each group of rolling rollers 61 is 8μm.

[0163] Example 8

[0164] The specific operating method and conditions are the same as in Example 1; the difference is that during the calendering process, the pressure of each set of pressing rollers 61 is 0.2 tons.

[0165] Example 9

[0166] The specific operating method and conditions are the same as in Example 1; the difference is that the composition of the molten liquid is selected from Li:graphene = 1:0.05.

[0167] Example 10

[0168] The specific operating methods and conditions are the same as in Example 1; the difference is that: the substrate 1 is selected from sodium battery negative electrode sheet (main material is hard carbon) (thickness: 150μm); sodium metal is used as the molten liquid; during the cooling and shaping process, 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 in each group of cooling rollers is 153μm.

[0169] During the calendering process, the temperature of the upper and lower pressure rolls 61 in each group is selected from 80 degrees Celsius. The gap between the pressure rolls 61 in each group is 146 μm. The pressure of the pressure rolls 61 is 0.5 tons.

[0170] Example 11

[0171] The specific operation method and conditions are the same as in Example 1; the difference is that a substrate heating mechanism 8 is added before the substrate 1 is coated; the substrate sequentially 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 coding mechanism 7, and the winding system 22 to complete the preparation of the composite tape; the specific steps of the substrate passing through the substrate heating mechanism 8 are as follows: 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 conveying of the roller 83; the substrate is heated under the action of a protective gas at a temperature of 220±10 degrees while being conveyed by the roller 83.

[0172] Comparative Example 1

[0173] The specific operation method and conditions are the same as in Example 1; the difference is that when the die head 31 coats the continuously supplied substrate 1, the molten liquid is not stirred.

[0174] Comparative Example 2

[0175] The specific operating method and conditions are the same as in Example 1; the difference is that the heating temperature of the mold head 31 is 40 degrees.

[0176] Comparative Example 3

[0177] The specific operation method and conditions are the same as in Example 1; the difference is that when the die head 31 is not coated with liquid, the die head stop 32 is not placed to cover the die head outlet 317.

[0178] Comparative Example 4

[0179] The specific operation method and conditions are the same as in Example 1; the difference is that during the cooling and shaping process, the temperature of both the upper cooling roller 51 and the lower cooling roller 52 is selected from 10 degrees.

[0180] Comparative Example 5

[0181] The specific operating methods and conditions are the same as in Example 1; the difference is that during the calendering process, the temperature of the upper and lower pressing rollers 61 in each group is selected from 50 degrees.

[0182] Comparative Example 6

[0183] The specific operation method and conditions are the same as in Example 1; the difference is that during the calendering process, the gap between the rollers 61 of each group of rolling rollers 61 is 4.5μm.

[0184] Comparative Example 7

[0185] The specific operation method and conditions are the same as in Example 1; the difference is that the manufacturing equipment and preparation steps of this utility model are not used; instead, conventional methods of existing technology are used to calender and composite lithium-ion battery negative electrode sheets with lithium foil; the specific steps are as follows: a 5μm thick and 150μm wide lithium foil is placed on a 122μm thick and 151μm wide negative electrode sheet, and then calendered and composited using a calender. During the calendering process, the temperature of both the upper and lower pressure rollers 61 is set to room temperature, the gap between the rollers 61 is 110μm, and the pressure of the rollers 61 is 0.5 tons.

[0186] Specific testing and methods: The width is calculated using a laser measuring instrument based on the differences in laser reflection spectra of different materials. The width value is then automatically generated with reference to the set width center value. The thickness is calculated using a X-ray thickness gauge based on the changes in X-ray penetration intensity, and the thickness value and range of variation are obtained.

[0187] Table 1

[0188]

[0189]

[0190]

[0191] Table 2

[0192]

[0193] As can be seen from the data in Tables 1 and 2, the coating width, thickness, and final dimensions of Examples 1 to 10 are all within the specified range, indicating that the manufacturing equipment and preparation steps of this invention can achieve a stable and uniform coating effect. A composite strip with a continuous and uniform coating layer 11 is obtained; this effectively solves the problems of uneven coating layer 11 and inconsistent thickness in the pre-lithiation of electrode sheets in the prior art. Furthermore, as can be seen from Table 2, the composite substrate 1 cells in the examples generally have high coulombic efficiency and good cycle performance, demonstrating that the manufacturing method and equipment of this invention have significant advantages and high industrial application value in improving the quality of composite strips, battery performance, and production efficiency.

[0194] In contrast, Comparative Examples 1 and 2, due to improper use of the die head, resulted in unstable coating width and thickness, as well as severe scratches on the composite tape and copper foil breakage. These problems seriously affected battery performance and production efficiency. Comparative Example 1, due to the lack of stirring of the molten liquid, resulted in uneven coating thickness and the presence of solidified particles, ultimately producing a composite tape with severe scratches. This is because, without stirring, the molten liquid easily forms solidified particles on the copper foil surface. These particles scratch the copper foil surface during rolling, leading to scratches on the composite tape surface and affecting battery performance and safety.

[0195] In Comparative Example 2, we can see that the composite tape caused copper foil breakage due to the presence of solidified particles during coating. This is because the heating temperature of the die 31 was too low, resulting in incomplete solidification of the coated molten liquid. The solidified particles adhered to the surface of the copper foil, causing uneven coating layer 11. The copper foil was prone to breakage during the rolling process, thus affecting the performance of the battery.

[0196] As can be seen from Comparative Example 3, compared with the manufacturing equipment of the embodiments, the present invention, using a combination of a die head and a die head block as a coating mechanism, is more conducive to achieving uniform coating of the molten liquid and avoids the generation of solidified particles. When the die head 31 is not performing the coating operation, Comparative Example 3 does not use the die head block 32 for masking treatment; this results in solidified particles appearing during the preparation of the composite tape, leading to copper foil breakage and preventing the successful preparation of a uniform and continuous composite tape for use. This is because without the use of the die head block 32 for masking treatment, the molten liquid is prone to solidifying and clogging the die head outlet 317; and it is also prone to air entry, molten liquid oxidation and contamination, forming solidified particles on the surface of the copper foil substrate 1 during subsequent coating operations. These particles will scratch the copper foil surface during the rolling process, causing the composite tape to break and affecting the performance and safety of the battery. Therefore, using the die head block 32 for masking treatment is more conducive to ensuring the integrity of the composite tape.

[0197] Examples 1-10 and Comparative Examples 4, 5, and 6 also demonstrate that the optimized preparation method of this invention is crucial for the successful preparation of continuous and uniform composite tapes.

[0198] In Comparative Example 4, the setting temperature was too low during the composite tape preparation process, causing molten metal to splash everywhere, making safe operation impossible. Consequently, the composite tape production could not be successfully completed. This was because the setting temperature was too low, preventing the molten metal from solidifying evenly on the copper foil surface, resulting in molten metal splashing everywhere, unsafe operation, and an inability to achieve a uniform coating effect.

[0199] In Comparative Example 5, the temperature of the spreading roller 61 selected in the composite tape preparation process was too low compared to that in the Example, resulting in noticeable scratches on the composite tape. This was due to the improper temperature setting of the spreading roller 61, leading to uneven solidification of the molten liquid on the copper foil surface, thus causing scratches. This uneven solidification process not only affected the surface quality of the composite tape but also reduced the performance of the battery. Therefore, selecting an appropriate temperature for the spreading roller 61 is crucial for ensuring the uniformity of the coating layer 11 and the battery performance.

[0200] In Comparative Example 6, the copper foil broke during the rolling process due to an excessively small roll gap. This demonstrates that the roll gap size needs precise control during coating to avoid unnecessary damage to the copper foil. A suitable roll gap setting ensures the uniformity of the coating layer 11 while preventing copper foil breakage, thus ensuring smooth production.

[0201] In Comparative Example 7, a composite strip was prepared by directly calendering and bonding lithium foil onto substrate 1 using conventional methods. We observed that the composite strip had no obvious scratches on its surface and exhibited high coulombic efficiency, but poor cycle performance. This is due to limitations in lithium foil thickness; the thinnest lithium foil currently available on the market is 5±1 μm thick. In Examples 1-9 and Comparative Examples 1-6, the main material of the negative electrode is graphite. The required pre-lithiation amount for graphite negative electrodes is 8-10%, corresponding to a lithium layer thickness of 3±1 μm. Comparative Example 6 involved excessive lithium addition, resulting in rapid capacity decay during battery cycling.

[0202] As can be seen from Example 10, the manufacturing equipment of this utility model is also suitable for sodium replenishment treatment of sodium-ion battery negative electrode sheets; indicating that the equipment of this utility model can not only successfully realize the pre-lithiation preparation of composite strips, but also be applicable to the preparation of other metal composite strips; it has high flexibility and applicability; and has high industrial practical value.

[0203] As can be seen from Examples 1-10 and Example 11, heating the substrate by the substrate heating mechanism 8 before coating is more conducive to reducing the contact angle of the lithium melt, which is beneficial to the preparation of 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.

[0204] In Example 1, the contact angle between the lithium metal solution and the substrate during coating was measured to be in the range of 30-60°. In Example 11, the contact angle between the lithium molten liquid and the heated substrate during coating was measured to be in the range of 1-10°. This indicates that the further optimization of this invention, by heating the substrate before coating, can further reduce the contact angle of the molten metal, thereby making it more conducive to the preparation of a thinner coating and maximizing its effect on battery performance.

[0205] It should be noted that the above description is only one of the embodiments of this utility model and is not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A die head, characterized in that, The mold head (31) has two parts: an upper mold head (311) and a lower mold head (312); the upper mold head (311) and the lower mold head (312) are closed to form a hollow liquid storage tank (313); The storage tank (313) has a rotatable stirring device (314) inside; The stirring device (314) is also provided with detachable sealing devices (315) at both ends; at least one of the sealing devices (315) is provided with a high-pressure protective gas inlet (3151) that communicates with the liquid storage tank (313).

2. The die head according to claim 1, characterized in that, 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 housed inside the liquid storage tank (313).

3. The die head according to claim 1, characterized in that, The upper mold head (311) and the lower mold head (312) are respectively provided with a port (3131) at the end of the liquid storage tank (313) so that the stirring device (314) can pass through. The inner wall of the port (3131) is provided with an inner wall groove (31311), and the stirring device (314) is provided with a channel (31312) that matches and fits into 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).

4. The die head according to claim 1, characterized in that, The sealing device (315) further includes a sealing cover plate (3152) and a cover plate protrusion (3153). The diameter of the sealing cover plate (3152) is larger than that of the cover plate protrusion (3153), and the cover plate protrusion (3153) is integrally formed with the cover plate protrusion (3153). The cover plate protrusion (3153) is sealed and inserted into the outer groove (31313) on the outer wall of the port (3131).

5. The die head according to claim 4, characterized in that, 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 air intake channel (3154) corresponding to the high pressure protective gas inlet (3151), and the air intake channel (3154) is connected to the inner wall groove (31311) to realize the air intake of the liquid storage tank (313).

6. The die head according to claim 1, characterized in that, The die head (31) also includes a gasket (316), which is disposed in the area between the liquid storage tank (313) and the edge of the die head. The gasket (316) has a gasket opening (3161) facing the edge of the die head, and the molten liquid is evenly distributed and discharged through the gasket opening (3161). The edge of the die head corresponding to one side of the gasket opening (3161) is the die head discharge port (317).

7. The die head according to claim 6, characterized in that, The gasket (316) is provided with at least two positioning pins (3162), which are used to fix the gasket (316) on the mold head (31).

8. The die head according to claim 1, characterized in that, The mold head (31) also includes a fine-tuning mechanism (318); the fine-tuning mechanism (318) is disposed on the upper mold head (311); the mold head (31) also has a mold head heating device (33).

9. The die head according to claim 8, characterized in that, The fine-tuning mechanism (318) includes an adjusting plate (3181) and at least two threaded screws (3182) arranged in parallel. The adjusting plate (3181) is provided with threaded holes (3183) corresponding to the threaded screws (3182). The threaded screws (3182) are connected to the adjusting plate (3181) through the threaded holes (3183). The setting position of the adjusting plate (3181) can be fixed relative to the position of the upper die head (311). The free end of the threaded screw (3182) acts on the upper die head (311) to change the opening size of the die head outlet (317) by applying a force to the upper die head (311).

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