Composite electrodes and their preparation methods, lithium-ion batteries

Abstract

This application provides a composite electrode, its preparation method, and a lithium-ion battery. The preparation method of the composite electrode includes the following steps: conveying an electrode sheet through an electrode sheet unwinding mechanism, such that the electrode sheet passes through the gap between a heating mechanism and a shaping roller assembly; conveying a solid electrolyte membrane through a solid electrolyte membrane unwinding mechanism located beside the electrode sheet unwinding mechanism, such that the solid electrolyte membrane passes through the gap between the shaping roller assembly and the electrode sheet; preheating the electrode sheet through the heating mechanism to obtain a preheated sheet; and rolling the preheated sheet and the solid electrolyte membrane together through the shaping roller assembly to prepare the composite electrode. The method in this application addresses the issues of good composite effect, inconsistent transverse compaction density, and poor transverse thickness consistency in the composite electrode.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a composite electrode and its preparation method, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are currently the mainstream energy storage devices with broad application prospects. With the continuous emergence of new technologies, the requirements for battery performance are becoming increasingly stringent. Traditionally, a solid electrolyte material layer is coated onto the surface of the positive / negative electrode to improve battery safety. However, the evaporation of the solvent in the coated solid electrolyte layer can easily lead to shrinkage and deformation of the electrode, affecting battery performance.

[0003] Therefore, the development of dry processes for preparing positive / negative electrode sheets and solid electrolyte membranes to improve battery safety has received widespread attention. However, in the rolling step of dry process preparation of composite electrodes, due to the thinning treatment of the electrode edges during production, the bonding of the solid electrolyte membrane with the electrode sheet can easily lead to poor bonding effect, inconsistent lateral compaction density, and poor lateral thickness consistency of the composite electrode sheet. This can have a significant impact on the safety performance and quality of lithium-ion batteries. Summary of the Invention

[0004] Based on this, the first aspect of this application provides a method for preparing composite electrodes, which overcomes the adverse effects of the "thick in the middle and thin at both ends" phenomenon of electrode electrodes on the rolling composite process and avoids the electrode being crushed; and the electrode electrode and the solid electrolyte membrane are subjected to uniform stress during the rolling process, which improves the consistency of the transverse thickness of the composite electrode.

[0005] A method for preparing a composite electrode includes the following steps:

[0006] The electrode sheet is conveyed by the electrode sheet unwinding mechanism, so that the electrode sheet passes through the gap between the heating mechanism and the shaping roller assembly.

[0007] The solid electrolyte membrane is conveyed by the solid electrolyte membrane unwinding mechanism located on the side of the electrode unwinding mechanism, so that the solid electrolyte membrane passes through the gap between the shaping roller assembly and the electrode.

[0008] A preheated sheet is obtained by preheating the electrode plates using a heating mechanism; and

[0009] Composite electrodes are prepared by roll pressing a preheated sheet and a solid electrolyte membrane together using a shaping roller assembly.

[0010] In some embodiments, a composite electrode is obtained by roll-pressing solid electrolyte membranes located on both sides of the electrode sheet onto the electrode sheet using a shaping roller assembly.

[0011] In some implementations, the electrode plates are preheated several times, with the temperature increasing progressively in each preheating cycle.

[0012] In some implementations, the preheating time is ≥2 seconds.

[0013] In some embodiments, an elastic element is provided between the shaping roller assembly and the solid electrolyte membrane.

[0014] In some embodiments, the elastic element is a protective film, which is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

[0015] In some embodiments, the elastic element is an adhesive layer that surrounds and covers the outside of the shaping roller assembly.

[0016] In some embodiments, a substrate is coated on the solid electrolyte membrane, and the method for preparing the composite electrode further includes the step of separating the substrate coated on the solid electrolyte membrane from the composite electrode.

[0017] In some embodiments, the method for preparing composite electrodes also includes cooling the composite electrodes.

[0018] In some embodiments, the method for preparing composite electrodes further includes:

[0019] Downstream of the shaping roller assembly, the composite electrode sheet is received by the composite electrode sheet winding mechanism;

[0020] The substrate is received by the substrate winding mechanism between the shaping roller assembly and the composite electrode winding mechanism;

[0021] The substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode unwinding mechanism.

[0022] In some embodiments, the method for preparing composite electrodes further includes:

[0023] The elastic element is conveyed via a protective film unwinding mechanism; the protective film unwinding mechanism is located between the solid electrolyte membrane unwinding mechanism and the shaping roller assembly; and

[0024] The elastic element is received by the protective film winding mechanism between the shaping roller assembly and the substrate winding mechanism.

[0025] The second aspect of this application provides a composite electrode sheet, which is prepared according to the preparation method provided in the first aspect above.

[0026] A third aspect of this application provides a lithium-ion battery comprising the composite electrode provided in the second aspect above.

[0027] The method for preparing the composite electrode sheet in this application involves preheating the electrode sheet before the roll forming step. Preheating increases the flexibility of the electrode sheet, improves its ductility, and enhances its plasticity. As a result, when the forming roller assembly rolls the electrode sheet and the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are more tightly bonded, improving the adhesion strength between the two layers and making it easier to achieve a tight composite effect.

[0028] In the method for preparing composite electrodes in this application, compared with the overall preheating of the electrode electrode and the solid electrolyte membrane, the structure of the roller pressing device for preheating the electrode electrode separately is simpler, and at the same time, the preheating of the electrode electrode is more thorough, without having to consider factors such as the slow preheating speed of the composite membrane and the different preheating temperatures of the solid electrolyte membrane.

[0029] The composite electrode preparation method of this application, during the rolling process of the shaping roller assembly, utilizes the buffer provided by the elastic element to adjust the stress on the electrode sheet and the solid electrolyte membrane during rolling, allowing the solid electrolyte membrane to better cover the electrode sheet. Furthermore, it ensures uniform stress on the electrode sheet and the solid electrolyte membrane during rolling, resulting in a more consistent lateral thickness of the electrode sheet after rolling. This avoids the adverse effects of the electrode sheet being thicker in the middle and thinner at both ends on the rolling composite process, preventing the electrode sheet from being crushed. The combined effect of the heating process and the elastic element improves the degree of bonding between the electrode sheet and the solid electrolyte membrane, enhancing the consistency of the lateral thickness of the composite electrode sheet. Moreover, the composite electrode prepared using the method of this application, when applied to batteries, helps improve the overall safety performance of the battery. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a flowchart of a method for preparing a composite electrode in one embodiment of this application.

[0032] Figure 2 This is a schematic diagram of the apparatus for preparing the composite electrode in Embodiment 1 of this application.

[0033] Figure 3 This is a schematic diagram of the apparatus for preparing the composite electrode in Embodiment 2 of this application.

[0034] Figure 4 This is a schematic diagram of the apparatus for preparing the composite electrode in Embodiment 3 of this application.

[0035] Figure 5 This is a schematic diagram of the apparatus for preparing the composite electrode in Embodiment 4 of this application.

[0036] Figure 6 This is a schematic diagram of the apparatus for preparing a composite electrode, which is a comparative example of this application.

[0037] Figure 7 This is a schematic diagram of the apparatus for preparing the composite electrode of Comparative Example 2 of this application.

[0038] Figure 8 This is a schematic diagram of the apparatus for preparing the comparative example of the three-composite electrode of this application.

[0039] Explanation of reference numerals in the attached figures

[0040] 11. Electrode unwinding mechanism; 12. Composite electrode winding mechanism;

[0041] 21. Solid electrolyte membrane unwinding mechanism; 22. Substrate winding mechanism;

[0042] 31. First shaping roller; 32. Second shaping roller;

[0043] 41. Protective film unwinding mechanism; 42. Protective film rewinding mechanism.

[0044] 51. First guide roller; 52. Second guide roller; 53. Third guide roller; 54. Fourth guide roller; 55. Fifth guide roller; 56. Sixth guide roller; 57. Seventh guide roller; 58. Eighth guide roller; 59. Ninth guide roller;

[0045] 71. First heating roller; 72. Second heating roller; 73. Third heating roller; 74. Cooling roller;

[0046] 81. Adhesive layer. Detailed Implementation

[0047] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0048] In the description of this application, it should be understood that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," or "third" may explicitly or implicitly include at least one of those features.

[0049] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0050] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0051] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means additional steps and components that may be added without affecting the final result. The compositions and methods / processes of this application comprise, consist of, and are substantially composed of the essential elements and limitations described herein, as well as any additional or optional components, parts, steps, or limitations described herein.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0053] See Figure 2-5 As shown, the composite electrode preparation apparatus of this application includes a shaping roller assembly, an electrode unwinding mechanism 11, a solid electrolyte membrane unwinding mechanism 21, a heating mechanism, and a composite electrode winding mechanism 12. The shaping roller assembly includes a first shaping roller 31 and a second shaping roller 32 symmetrically arranged on both sides of the electrode; the connecting line between the axes of the first shaping roller 31 and the second shaping roller 32 is perpendicular to the conveying direction of the electrode.

[0054] The electrode sheet unwinding mechanism 11 is located upstream of the shaping roller assembly and is used to unwind the electrode sheet and then transport the electrode sheet so that it passes through the gap between the first shaping roller 31 and the second shaping roller 32.

[0055] It is understood that the electrode in this application is either a positive electrode or a negative electrode.

[0056] The solid electrolyte membrane unwinding mechanism 21 is located upstream of the shaping roller assembly, and more specifically, between the electrode unwinding mechanism 11 and the shaping roller assembly. The solid electrolyte membrane unwinding mechanism 21 is used to unwind the solid electrolyte membrane and then transport it through the gap between the first shaping roller 31 and the second shaping roller 32. More specifically, the solid electrolyte membrane unwinding mechanism 21 allows the solid electrolyte membrane to pass through the gap between the electrode sheet and the shaping roller assembly.

[0057] In some embodiments, there are two solid electrolyte membrane unwinding mechanisms 21, located on both sides of the electrode sheet unwinding mechanism 11, and then the solid electrolyte membrane is conveyed so that the two solid electrolyte membranes pass through the gap between the first shaping roller 31 and the second shaping roller 32, and the electrode sheet is located in the middle of the two solid electrolyte membranes.

[0058] Optionally, two solid electrolyte membrane unwinding mechanisms 21 are symmetrically arranged on both sides of the electrode sheet unwinding mechanism 11.

[0059] The heating mechanism is located between the electrode unwinding mechanism 11 and the shaping roller assembly, and is used to preheat the electrode sheet and / or solid electrolyte membrane.

[0060] In some implementations, the heating mechanism is a heating roller.

[0061] In some embodiments, the number of heating rollers in the composite electrode preparation apparatus is not particularly limited, and the specific number of heating rollers can be increased or decreased according to the actual situation.

[0062] In some embodiments, the number of heating rollers can be one, namely the first heating roller 71.

[0063] In some embodiments, there may be multiple heating rollers, and the temperature of the heating rollers gradually increases along the direction of travel of the electrode sheet, making the preheating effect more uniform. Specifically, the heating rollers along the direction of travel of the electrode sheet are, in sequence, a first heating roller 71, a second heating roller 72, and a third heating roller 73. The number of the first heating roller 71, the second heating roller 72, and the third heating roller 73 may be one, two, or more, respectively, without particular limitation.

[0064] In some implementations, the heating roller is preheated for ≥2 seconds.

[0065] In the composite electrode preparation method of this application, the heating roller is used to preheat the electrode sheet separately, while the solid electrolyte membrane is not preheated. The overall structure of the preparation device that preheats the electrode sheet separately is relatively simple. During preheating, it is only necessary to consider whether the electrode sheet is preheated sufficiently, without considering factors such as the different preheating rates or required preheating temperatures of the electrode sheet, solid electrolyte membrane, and protective film.

[0066] The composite electrode winding mechanism 12 is located downstream of the shaping roller assembly. It is used to provide tension to the electrode sheet along the direction of electrode sheet movement, and to receive the composite electrode sheet obtained after being rolled and compounded by the shaping roller assembly and complete the winding action.

[0067] It is understood that this application does not specifically limit the preheating method. Preheating methods can include contact preheating, forced-air preheating, or radiation preheating to preheat the electrode sheets, solid electrolyte membrane, and protective film. Preferably, an S-shaped roller contact heating method is used. Using rollers with a large wrap angle or multiple small heating rollers can save space. This achieves rapid heating at a lower cost, with a short preheating stroke, fast heat transfer, and independent temperature control for any heating roller in the contact preheating process.

[0068] Before entering the shaping roller assembly, the electrode sheet undergoes a preheating treatment. The preheated electrode sheet softens compared to before preheating, which improves the ductility of the electrode sheet. As a result, when the solid electrolyte membrane and the electrode sheet are rolled together by the first shaping roller assembly, the solid electrolyte membrane and the electrode sheet are more tightly bonded, improving the bonding strength between them and further enhancing the composite effect.

[0069] In some embodiments, an elastic element is provided between the first shaping roller 31 and the second shaping roller 32.

[0070] In the production process of electrode sheets, the edges of the electrode sheets are usually thinned in order to ensure the smooth progress of the subsequent rolling process. However, the existence of the thinned area of ​​the electrode sheet affects the adhesion between the solid electrolyte membrane and the electrode sheet.

[0071] Surprisingly, the composite electrode preparation apparatus of this application utilizes the buffer provided by the elastic element during rolling, which allows the solid electrolyte membrane to better cover the electrode sheet; at the same time, during the rolling process of the shaping roller assembly, the electrode sheet is thicker in the middle, resulting in greater stress in the middle area than in the edge area, and the lateral thickness of the electrode sheet tends to be uniform after rolling.

[0072] The elastic layer is made of a flexible material that undergoes elastic deformation under pressure. The slight elastic deformation makes the thickness of the middle area and the thinned area of ​​the electrode sheet tend to be consistent under pressure, which can better adhere to the solid electrolyte membrane.

[0073] The yield limit of the elastic element satisfies the following condition: when the solid electrolyte membrane and the electrode sheet pass through the gap in the middle of the shaping roller assembly, the solid electrolyte membrane and the electrode sheet undergo plastic deformation, while the deformation of the elastic element becomes elastic deformation.

[0074] Elastic deformation refers to the change in the relative positions of points in a solid caused by an external force. When the external force is removed, the solid returns to its original shape, which is called elastic deformation.

[0075] When an object is subjected to a large force outside its elastic limit, it may break or deform and fail to return to its original shape. This phenomenon is called plastic deformation.

[0076] In some embodiments, the width of the elastic element is greater than or equal to the minimum width of the solid electrolyte membrane or the electrode sheet.

[0077] In some embodiments of the present invention, the flexible material is a polymer.

[0078] This application does not impose any special restrictions on the material of the polymer. For example, it can be plastics such as polytetrafluoroethylene, polyethylene terephthalate, polypropylene, and polyacrylonitrile, or rubbers such as Hypalon rubber, silicone rubber, and fluororubber, or elastic materials such as silicone that can undergo a certain degree of deformation.

[0079] This application does not impose any particular limitation on the thickness of the elastic element. Any necessary adjustments to the thickness of the elastic element without departing from the inventive concept of this application can be understood as being within the scope of protection of this application.

[0080] In some embodiments, the elastic element is an adhesive layer 81 that surrounds and covers the outside of the two shaping roller assemblies.

[0081] In some embodiments, the elastic element is a protective film, which is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

[0082] Adaptively, the composite electrode preparation apparatus of this application further includes a protective film unwinding mechanism 41 for unwinding the protective film. The protective film unwinding mechanism 41 is located upstream of the shaping roller assembly, positioned between the solid electrolyte membrane unwinding mechanism 21 and the shaping roller assembly, and is used to unwind the protective film. The protective film is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

[0083] This application does not impose any special requirements on the structure of the protective film. Without departing from the inventive concept, any known film layer capable of undergoing a certain degree of elastic deformation under pressure can be used in this application. These are merely illustrative examples and not limitations on the scope of protection. The protective film can be selected from polymer films or nonwoven fabrics. Nonwoven fabrics include, but are not limited to, PP-based nonwoven fabrics, PE-based nonwoven fabrics, PET-based nonwoven fabrics, PAN-based nonwoven fabrics, PTFE-based nonwoven fabrics, Celgard nonwoven fabrics, etc.; polymer films can be selected from PVDF films, PE films, PP films, PE / PP films, PE / PP / PE films, PP / PE / PP films, PTFE films, silicone release films, fluorine release films, PET films, non-silicone release films, etc. It is understood that the protective film can also be a multilayer structure composed of two or more polymer films and / or nonwoven fabrics.

[0084] This application does not specifically limit the thickness of the protective film. Without departing from the inventive concept of this application, any conventional adjustment of the thickness of the protective film to adjust the rolling effect should be considered within the scope of protection of this application. It is understood that when the protective film is a multi-layer structure, the thickness of the protective film should be the sum of the thicknesses of the multi-layer structure.

[0085] In some embodiments, the composite electrode preparation apparatus further includes a protective film winding mechanism 42, which is located downstream of the shaping roller assembly and between the shaping roller assembly and the composite electrode winding mechanism 12, for providing tension to the protective film and winding up the protective film.

[0086] In some embodiments, the apparatus for preparing composite electrodes also includes a substrate winding mechanism 22.

[0087] When a substrate is disposed on the solid electrolyte membrane, the substrate covers the side of the solid electrolyte membrane away from the electrode sheet. After the electrode sheet and the solid electrolyte membrane are rolled together by the shaping roller assembly to form a composite electrode sheet, the substrate needs to be separated. This separation is achieved by a substrate winding mechanism 22 located downstream of the shaping roller assembly. During the separation process, the substrate winding mechanism 22 applies tension to the substrate covering the solid electrolyte membrane, causing the substrate to separate from the composite electrode sheet, and, if necessary, winding up the substrate.

[0088] The number of substrate winding mechanisms 22 corresponds to the number of solid electrolyte membrane unwinding mechanisms 21, and the substrate winding mechanisms 22 and solid electrolyte membrane unwinding mechanisms 21 are located on the same side of the electrode sheet unwinding mechanism 11.

[0089] This application does not specifically limit the type of substrate. Without departing from the inventive concept of this application, any known material that provides a certain supporting function, facilitates the formation of electrolyte material film, and can be separated from the solid electrolyte membrane after rolling can be used in this application. This is merely an illustrative example and not a limitation on the scope of protection. The substrate is selected from one or more of the following: silicone oil release film, fluorine release film, PET film, PP film, PE film, PE / PP film, PP / PE / PP film, PE / PP / PE film, and non-silicone release film.

[0090] In some embodiments, the apparatus for preparing composite electrodes also includes guide rollers.

[0091] Optionally, a guide roller is located between the electrode unwinding mechanism 11 and the shaping roller assembly to provide guidance for the electrode sheet. Alternatively, a guide roller can be provided between the shaping roller assembly and the composite electrode winding mechanism 12 to provide guidance for the winding of the composite electrode sheet.

[0092] Optionally, a guide roller is located between the solid electrolyte membrane unwinding mechanism 21 and the shaping roller assembly to provide guidance for the solid electrolyte membrane. Alternatively, a guide roller can be provided between the shaping roller assembly and the substrate winding mechanism 22 to guide the substrate separated from the composite electrode and covering the solid electrolyte membrane.

[0093] Optionally, a guide roller is located between the protective film unwinding mechanism 41 and the setting roller assembly to provide guidance for the protective film. Alternatively, a guide roller can be provided between the setting roller assembly and the protective film winding mechanism 42 to provide guidance for the recycling of the protective film.

[0094] In some embodiments, the composite electrode preparation apparatus further includes a cooling roller 74 located between the shaping roller assembly and the composite electrode winding mechanism 12, for cooling the composite electrode emerging from the gap in the shaping roller assembly. This application uses the cooling roller 74 to reduce the temperature of the composite electrode, enabling continuous winding and improving production efficiency; simultaneously, the cooling roller 74 also provides shaping treatment for the composite electrode.

[0095] In some embodiments, the number of cooling rollers 74 can be one or more, preferably two.

[0096] In some embodiments, a guide roller is provided between the shaping roller assembly and the cooling roller 74, and / or a guide roller is provided between the cooling roller 74 and the composite electrode winding mechanism 12, for adjusting the cooling time of the composite electrode.

[0097] In some embodiments, the number of cooling rollers 74 and guide rollers in the composite electrode preparation apparatus is not particularly limited, and the specific number can be increased or decreased according to the actual situation.

[0098] In some embodiments, the composite electrode preparation apparatus further includes an unwinding correction assembly and an electrode static eliminator assembly arranged sequentially along its unwinding path. The unwinding correction assembly can correct the unwinding and running paths of the electrode sheets and solid electrolyte membrane, ensuring that the initial material lines remain at the same level. The main material's unwinding and take-up mechanism uses single-station correction, while the unwinding and take-up of other materials uses a cantilever type, all with correction capabilities. The static eliminator assembly performs static elimination treatment on both sides of the electrode sheets, reducing friction between the electrode sheets and the conveyor rollers. It is understood that, without departing from the inventive concept of this application, known functional components or structures can be used in this application throughout the entire process from winding, rolling, and unwinding.

[0099] In some embodiments, the composite electrode preparation apparatus also includes a tension control device.

[0100] In some embodiments, the tension control device includes a plurality of tension control elements disposed upstream of the shaping roller assembly, which are used to control the unwinding tension of the electrode sheet, the solid electrolyte membrane and the protective film, respectively.

[0101] In some embodiments, the tension control device includes multiple tension control elements disposed downstream of the shaping roller assembly, which are used to control the winding tension of the composite electrode, the substrate and the protective film, respectively.

[0102] In some embodiments, the composite electrode preparation apparatus further includes a thickness measuring mechanism. After the composite electrode is rolled and laminated by the shaping roller assembly, it passes the inspection of the thickness measuring mechanism and then enters the composite electrode winding mechanism 12 for winding. In some embodiments, the heating roller and cooling roller 74 also include sensors for detecting the surface temperature of the composite electrode.

[0103] In some embodiments, the tension force is applied to the shaping roller assembly by means of upper and lower rollers or heating rollers, preferably heating rollers, which have a larger roller diameter and are equipped with a heating device inside.

[0104] In some embodiments, the width of the shaping roller assembly is 500-800 mm, including but not limited to 500 mm, 550 mm, 600 mm, 650 mm, 700 mm, 750 mm, and 800 mm. Preferably, it is 550-650 mm.

[0105] In some embodiments, the diameter of the shaping roller assembly is 300-500 mm, including but not limited to 300 mm, 350 mm, 400 mm, 450 mm, and 500 mm. Preferably, it is 350-450 mm.

[0106] In some embodiments, the tonnage of the shaping roller assembly is 10-15 tons, including but not limited to 11 tons, 12 tons, 13 tons, 14 tons, and 15 tons. Preferably, it is 11-13 tons.

[0107] In some embodiments, the mechanical speed of the shaping roller assembly is 10-30 m / min, including but not limited to 10 m / min, 15 m / min, 20 m / min, and 25 m / min.

[0108] It is understandable that a higher conveyor speed in the entire composite electrode preparation apparatus results in higher production efficiency, but excessively high speeds can easily lead to problems such as belt breakage between the conveyor electrode and the solid electrolyte membrane. This application does not impose any special requirements on the residence time of the electrode sheet and the solid electrolyte membrane within the gap of the shaping roller assembly. Any adjustments to the residence time made without inventive effort, provided they do not contradict the inventive concept of this application, should be understood as falling within the scope of protection of this application.

[0109] In some embodiments, the linear speeds of the first shaping roller assembly 31 and the second shaping roller assembly 32 are kept consistent, and the linear speeds of the electrode unwinding mechanism 11 and the composite electrode winding mechanism 12 are also kept consistent, thereby improving the consistency of the entire composite electrode rolling process and enhancing the consistency of the composite electrode.

[0110] See Figures 2-5 Based on the structure of the composite electrode preparation apparatus, the composite electrode preparation method of this application includes the following steps: unwinding an electrode sheet through an electrode sheet unwinding mechanism 11 and conveying the electrode sheet to a composite electrode sheet winding mechanism 12, so that the electrode sheet passes sequentially through the gap between the heating roller, the first shaping roller 31, and the second shaping roller 32; conveying a solid electrolyte membrane through a solid electrolyte membrane unwinding mechanism 21 located on the side of the electrode sheet unwinding mechanism 11, so that the solid electrolyte membrane passes through the gap between the shaping roller assembly and the electrode sheet; then rolling and bonding the composite electrode sheet through the first shaping roller 31 and the second shaping roller 32; during the rolling and bonding process, an elastic element is provided between the shaping roller assembly and the solid electrolyte membrane; finally, downstream of the shaping roller assembly, the composite electrode sheet is received by the composite electrode sheet winding mechanism 12.

[0111] In some embodiments, the composite electrode includes an electrode sheet and solid electrolyte membranes located on both sides of the electrode sheet. After transporting the electrode sheet, the solid electrolyte membrane is unwound by two solid electrolyte membrane unwinding mechanisms 21 located on both sides of the electrode sheet unwinding mechanism 11 and fed into the shaping roller assembly, such that the two solid electrolyte membranes pass through the gap between the first shaping roller 31 and the second shaping roller 32. In the gap between the first shaping roller 31 and the second shaping roller 32, the two solid electrolyte membranes, the electrode sheet located between the two solid electrolyte membranes, and the elastic element located on the outer side of the two solid electrolyte membranes are bonded together in pairs. Under the rolling pressure of the shaping roller assembly, the solid electrolyte membranes are composited on both sides of the electrode sheet, thus obtaining the composite electrode.

[0112] In some embodiments, the solid electrolyte membrane is formed independently, meaning that the solid electrolyte membrane can be formed and maintain its integrity without the aid of a substrate. In this case, after the electrode sheet and the solid electrolyte membrane enter the gap of the shaping roller assembly, a composite electrode sheet is formed under the pressure of the shaping roller assembly, and then the composite electrode sheet is wound up by the electrode sheet winding mechanism.

[0113] In some embodiments, a substrate layer is coated on the solid electrolyte membrane to provide support for it. When the solid electrolyte membrane unwinding mechanism 21 transports the solid electrolyte membrane, the substrate is positioned on the side of the solid electrolyte membrane away from the electrode sheet. After the solid electrolyte membrane and electrode sheet are laminated, the substrate is separated from the laminated electrode sheet. Specifically, the substrate can be received by substrate winding mechanisms 22 located on either side of the laminated electrode sheet winding mechanism 12, with the substrate winding mechanisms 22 situated between the shaping roller assembly and the laminated electrode sheet winding mechanism 12.

[0114] In some embodiments, the elastic element is an adhesive layer 81 that surrounds and covers the outer sides of the first shaping roller 31 and the second shaping roller 32. When the shaping roller assembly rotates, the adhesive layer 81 rotates with the shaping roller assembly; and when the shaping roller assembly rolls the solid electrolyte membrane and / or electrode sheet, the adhesive layer 81 provides a buffering effect on the solid electrolyte membrane and / or electrode sheet, allowing the solid electrolyte membrane to better cover one or both sides of the electrode sheet, while simultaneously improving the consistency of the transverse thickness of the rolled electrode sheet.

[0115] In some embodiments, the elastic element is an adhesive layer 81 that surrounds and covers the outer side of the shaping roller assembly. See also Figure 5 As shown, the forming roller assembly contains, in sequence, an adhesive layer 81, a solid electrolyte membrane, an electrode sheet, another solid electrolyte membrane, and the adhesive layer 81. The length of the adhesive layer 81 along the axial direction of the forming roller assembly can be slightly greater than the axial length of the forming roller assembly. During rolling, the adhesive layer 81 rotates together with the forming roller assembly.

[0116] In some embodiments, the elastic element is a protective film. The protective film is unwound through two protective film unwinding mechanisms 41 located on the side of the solid electrolyte membrane unwinding mechanism 21 away from the electrode sheet. The protective film unwinding mechanism 41 conveys the protective film to the shaping roller assembly so that the two protective films pass through the gap between the first shaping roller 31 and the second shaping roller 32, respectively. In the gap between the first shaping roller 31 and the second shaping roller 32, the protective film, solid electrolyte membrane, electrode sheet, solid electrolyte membrane, and protective film are sequentially distributed and bonded together in pairs. Under the rolling pressure of the shaping roller assembly, the solid electrolyte membrane is composited on both sides of the electrode sheet, thereby obtaining a composite electrode sheet.

[0117] Optional, such as Figure 2-4 As shown, in the shaping roller assembly and upstream of it, the electrode sheets on the electrode sheet unwinding mechanism 11 are guided by the first guide roller 51 to the first heating roller 71, and then preheated by the second heating roller 72 and the third heating roller 73, and then guided by the fourth guide roller 54 to the shaping roller assembly; the solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 to the shaping roller assembly; the protective film located on both sides of the electrode sheet unwinding mechanism 11 is guided by the third guide roller 53 to the shaping roller assembly; then, through the gap between the first shaping roller 31 and the second shaping roller 32, under the rolling pressure of the first shaping roller 31 and the second shaping roller 32, the composite of the protective film, the solid electrolyte membrane, the electrode sheet, the solid electrolyte membrane and the protective film is completed.

[0118] Optionally, the solid electrolyte membrane and the protective film are first bonded together upstream of the shaping roller assembly, and then come into contact with the electrode sheet after rotating with the shaping roller assembly. For example, at the third guide roller 53, the protective film is bonded to the side of the solid electrolyte membrane away from the electrode sheet. Then, the solid electrolyte membrane and the protective film rotate together with the first shaping roller 31 or the second shaping roller 32 to the gap between the first shaping roller 31 and the second shaping roller 32, and the side of the solid electrolyte membrane away from the protective film comes into contact with and is bonded to the electrode sheet.

[0119] Optional, such as Figure 5 As shown, in the shaping roller assembly and upstream of it, the electrode sheet on the electrode sheet unwinding mechanism 11 is guided by the first guide roller 51 to the first heating roller 71, then preheated by the second heating roller 72 and the third heating roller 73, and then guided by the fourth guide roller 54 to the shaping roller assembly; the solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 to the shaping roller assembly; the outer sides of the first shaping roller 31 and the second shaping roller 32 are covered with an adhesive layer 81, and the composite of the electrode sheet and the solid electrolyte membrane is completed under the rolling pressure of the first shaping roller 31 and the second shaping roller 32.

[0120] During roll forming, the shaping roller assembly applies tension to the electrode sheet and the solid electrolyte membrane. The protective film and adhesive layer 81 are located between the shaping roller assembly and the solid electrolyte membrane, playing a buffering role. This ensures that the force on each point of the electrode sheet and the solid electrolyte membrane is relatively uniform. Ultimately, the solid electrolyte membrane in the composite electrode sheet almost completely covers the electrode sheet, resulting in better bonding between the electrode sheet and the solid electrolyte membrane. This improves the consistency of the transverse thickness of the composite electrode sheet and also increases the compaction density.

[0121] In some implementations, the protective film and the substrate can be separated from the composite electrode simultaneously.

[0122] Optionally, downstream of the setting roller assembly, such as Figure 2 As shown, the protective film, substrate, and shaping roller assembly are bonded and separated. Specifically, the protective film and substrate are guided by the fifth guide roller 55 to the protective film winding mechanism 42 and the substrate winding mechanism 22, respectively, whereby the protective film and substrate are separated from the composite electrode sheet to obtain the composite electrode sheet. The composite electrode sheet is guided by the sixth guide roller 56 to the cooling roller 74, and then by the seventh guide roller 57 to the composite electrode sheet winding mechanism 12, completing the winding of the composite electrode sheet.

[0123] like Figure 5 As shown, the substrate is bonded and separated from the shaping roller assembly. Specifically, the substrate is guided by the fifth guide roller 55 and then reaches the substrate winding mechanism 22, where it is separated from the composite electrode to obtain the composite electrode. The composite electrode is guided by the sixth guide roller 56 and then reaches the cooling roller 74, and then by the seventh guide roller 57 and finally reaches the composite electrode winding mechanism 12, completing the winding of the composite electrode.

[0124] Optionally, downstream of the setting roller assembly, the protective film and substrate can reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively via different guide rollers, such as... Figure 3 As shown, the separation angle between the substrate and the composite electrode is not controlled. Specifically, the protective film is guided by the fifth guide roller 55 and then reaches the protective film winding mechanism 42; the substrate is guided by the ninth guide roller 59 and the eighth guide roller 58 and then reaches the substrate winding mechanism 22, and the path between the ninth guide roller 59 and the eighth guide roller 58 is a straight line; the protective film and the substrate are separated from the composite electrode.

[0125] Optionally, downstream of the setting roller assembly, the protective film and substrate can reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively via different guide rollers, such as... Figure 4As shown, the separation angle between the substrate and the composite electrode is controlled. Specifically, the protective film is guided by the fifth guide roller 55 and then reaches the protective film winding mechanism 42; the substrate is guided by the ninth guide roller 59 and the eighth guide roller 58 in sequence and then reaches the substrate winding mechanism 22. The routing between the ninth guide roller 59 and the eighth guide roller 58 is an S-shaped curve; the protective film and the substrate are separated from the composite electrode.

[0126] This application provides a method for preparing composite electrodes using the aforementioned composite electrode preparation apparatus, such as... Figure 1 As shown, it includes the following steps:

[0127] S10. Preheat the electrode plates;

[0128] S20. A composite electrode is prepared by roll pressing the preheated electrode sheet and the solid electrolyte membrane together using a shaping roller assembly; an elastic element is provided between the shaping roller assembly and the solid electrolyte membrane.

[0129] In some embodiments, the elastic element is a protective film, which is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

[0130] See Figure 2-4 As shown, a protective film, a solid electrolyte membrane, electrode plates, and another solid electrolyte membrane are sequentially distributed among the shaping roller assemblies. The protective film originates upstream of the shaping roller assembly, is transported to the shaping roller assembly, passes through the gap between the shaping roller assembly and the solid electrolyte membrane, is rolled, and continues downstream of the shaping roller assembly until it is recycled. Therefore, the protective film of this application can be reused repeatedly, saving production and manufacturing costs while reducing environmental damage and improving production efficiency.

[0131] In some embodiments, the elastic element is an adhesive layer 81 that surrounds and covers the outside of the shaping roller assembly.

[0132] In some embodiments, a composite electrode is obtained by roll-pressing solid electrolyte membranes located on both sides of the electrode sheet onto the electrode sheet using a shaping roller assembly.

[0133] It is understandable that in the rolled composite electrode, the solid electrolyte layer is bonded to the electrode sheet. The solid electrolyte membrane being located on both sides of the electrode sheet means that a solid electrolyte membrane is bonded to both sides of the electrode sheet via pressure rollers.

[0134] In some embodiments, the electrode sheet is preheated several times, with the temperature increasing progressively in each preheating cycle. This progressively increasing temperature ensures more uniform heating across the electrode sheet, resulting in a tighter subsequent roll forming process.

[0135] In some embodiments, the electrode sheet is preheated three times by a first heating roller 71, a second heating roller 72, and a third heating roller 73.

[0136] In some implementations, the heating roller is preheated for ≥2 seconds.

[0137] In some embodiments, a substrate is covered on the side of the solid electrolyte membrane away from the electrode sheet, and the method for preparing the composite electrode sheet further includes the step of separating the substrate from the composite electrode sheet.

[0138] In some implementations, the substrate can be wound up and recycled downstream of the shaping roller assembly by separating the substrate from the composite electrode by the substrate winding mechanism 22.

[0139] In some embodiments, the preparation method of the composite electrode further includes the following step: cooling the composite electrode.

[0140] In some embodiments, a cooling roller 74 is provided to cool the composite electrode sheet, thereby reducing the temperature of the composite electrode sheet and enabling continuous winding of the composite electrode sheet, which improves production efficiency. At the same time, the cooling roller 74 also provides shaping treatment for the composite electrode sheet.

[0141] In some embodiments, the method for preparing composite electrodes further includes:

[0142] Downstream of the shaping roller assembly, the composite electrode is received by the composite electrode winding mechanism 12;

[0143] Between the shaping roller assembly and the composite electrode winding mechanism 12, the substrate is received by the substrate winding mechanism 22;

[0144] The substrate winding mechanism 22 and the solid electrolyte membrane unwinding mechanism 21 are located on the same side of the electrode sheet unwinding mechanism 11.

[0145] In some embodiments, the method for preparing composite electrodes further includes:

[0146] The elastic element is conveyed via the protective film unwinding mechanism 41; the protective film unwinding mechanism 41 is located between the solid electrolyte membrane unwinding mechanism 21 and the shaping roller assembly; and

[0147] The elastic element is received by the protective film winding mechanism 42 between the shaping roller assembly and the substrate winding mechanism 22.

[0148] The method for preparing the composite electrode sheet in this application involves preheating the electrode sheet before the roll forming step. Preheating increases the flexibility of the electrode sheet, improves its ductility, and enhances its plasticity. As a result, when the forming roller assembly rolls the electrode sheet and the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are more tightly bonded, improving the adhesion strength between the two layers and making it easier to achieve a tight composite effect.

[0149] In the method for preparing composite electrodes in this application, compared with the overall preheating of the electrode electrode and the solid electrolyte membrane, the structure of the roller pressing device for preheating the electrode electrode separately is simpler, and at the same time, the preheating of the electrode electrode is more thorough, without having to consider factors such as the slow preheating speed of the composite membrane and the different preheating temperatures of the solid electrolyte membrane.

[0150] As mentioned in the background section, traditional forming roller assemblies have high strength but poor deformation resistance. The electrode sheets are trimmed to facilitate the rolling process, resulting in a structure that is thicker in the middle and thinner at both ends. Due to the inconsistent lateral thickness of the electrode sheets, the edge areas of the electrode sheets remain separated from the solid electrolyte membrane when it is bonded to the electrode sheets. When the rolling equipment performs roll forming on the electrode sheets and solid electrolyte membrane, the different rolling forces exerted on the middle and edge areas of the electrode sheets by the steel rollers make it difficult for the electrode sheets and solid electrolyte membrane to bond tightly, resulting in ineffective bonding. This leads to inconsistent lateral compaction density and poor consistency of the composite electrode sheets. In severe cases, electrode sheet breakage may occur, significantly impacting the safety performance and quality of lithium-ion batteries.

[0151] The composite electrode preparation method of this application, during the rolling process of the shaping roller assembly, utilizes the buffer provided by the elastic element to adjust the stress on the electrode sheet and the solid electrolyte membrane during rolling, allowing the solid electrolyte membrane to better cover the electrode sheet. Furthermore, it ensures uniform stress on the electrode sheet and solid electrolyte membrane during rolling, resulting in a more consistent lateral thickness of the electrode sheet after rolling. This avoids the adverse effects of the electrode sheet being thicker in the middle and thinner at both ends on the rolling composite process, preventing the electrode sheet from being crushed. It also improves the degree of bonding between the electrode sheet, solid electrolyte membrane, and protective film, enhancing the consistency of the lateral thickness of the composite electrode sheet. Moreover, when the composite electrode sheet prepared using this method is applied to a battery, it can effectively prevent powder shedding that may occur during charge-discharge cycles, thus improving the battery's cycle performance and contributing to enhanced overall battery safety.

[0152] The composite process in this application is carried out under dry conditions, which differs from traditional wet electrode preparation methods. Traditional wet composite electrode preparation involves first preparing a solid electrolyte slurry, then coating the solid electrolyte slurry onto the electrode sheet, or vice versa, preparing an electrode slurry and then coating the electrode slurry onto a solid electrolyte membrane. This application's preparation process does not use solvents, eliminating the cumbersome subsequent drying step and effectively reducing production costs.

[0153] It is understood that dry process refers to the preparation of related electrode sheets and electrolyte membranes without the addition of solvents; the technical solutions that may use trace amounts of liquid lubricants or other liquid additives during the rolling process should still be within the scope of protection of this application.

[0154] In some embodiments, both the electrode sheets and the solid electrolyte membrane are prepared by a dry process.

[0155] In some embodiments, at least one of the electrode sheet and the solid electrolyte membrane is prepared by a dry process.

[0156] In some embodiments, both the electrode sheets and the solid electrolyte membrane are prepared by a wet process.

[0157] It is understandable that electrode sheets and solid electrolyte membranes are preferably prepared under dry conditions, so that solvents are no longer needed in the entire electrode preparation process.

[0158] It is understandable that the preparation process of the electrode sheet and the solid electrolyte membrane is independent of the preparation process of the composite electrode. That is, if the wet process is used, the electrode sheet goes through the processes of coating, drying and rolling.

[0159] In some embodiments, the electrode sheet is a positive electrode sheet. Positive electrode materials, especially high-nickel ternary materials with high energy density, are prone to undesirable side reactions with electrolytes, especially non-aqueous electrolytes. These side reactions cause a decrease in battery performance and create potential safety hazards. Composite solid electrolyte layers on the surface of the positive electrode are beneficial to improving battery safety.

[0160] The positive electrode sheet comprises an active material layer and a current collector layer. In the dry preparation of the positive electrode sheet, the active material, conductive agent and binder are first stirred to obtain a positive electrode mixture; after the mixture is subjected to fibrous treatment, a fibrous mixture of the positive electrode is obtained; the fibrous mixture of the positive electrode and the current collector layer are then rolled together to obtain the positive electrode sheet.

[0161] In some implementations, the fiberization methods include, but are not limited to, air jet milling, high-speed mixing, mechanical fusion, twin-screw extrusion, etc.

[0162] The positive electrode active material layer is formed of a positive electrode active material containing one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. The positive electrode active material layer has a thickness greater than or equal to about 1 μm and less than or equal to about 1,000 μm.

[0163] The positive electrode active material is one of layered oxides, spinel, and polyanionic materials. For example, layered oxides (e.g., rock salt layered oxides) contain one or more lithium-based positive electrode active materials selected from: LiCoO2 (LCO), LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi 1-x-y Co x Al y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi x Mn 1-x O2 (where 0 ≤ x ≤ 1), and Li 1+x MO2 (where M is one of Mn, Ni, Co, and Al and 0 ≤ x ≤ 1). Spinel contains one or more lithium-based cathode active materials selected from the following: LiMn2O4 (LMO) and LiNi. x Mn 1.5 O4. Olivine type comprises one or more lithium-based cathode active materials, LiMPO4 (where M is at least one of Fe, Ni, Co, and Mn). Polyanionic cations comprise, for example, phosphates such as LiV2(PO4)3 and / or silicates such as LiFeSiO4.

[0164] In some embodiments, one or more lithium-based cathode active materials may optionally be coated (e.g., by LiNbO3 and / or Al2O3) and / or may be doped (e.g., by magnesium (Mg)). Furthermore, in some embodiments, one or more lithium-based cathode active materials may optionally be mixed with one or more conductive materials that provide electronic conduction pathways and / or at least one polymeric binder material that improves the structural integrity of the cathode. For example, the cathode active material layer may comprise more than or equal to about 30% by weight and less than or equal to about 99% by weight of one or more lithium-based cathode active materials; more than or equal to about 0% by weight and less than or equal to about 30% by weight of conductive materials; and more than or equal to about 0% by weight and less than or equal to about 20% by weight of binder.

[0165] In some embodiments, the adhesive includes polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

[0166] In some embodiments, the conductive material may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0167] It is understood that the examples of positive electrode active materials, binders, and conductive materials mentioned above are merely illustrative. Without departing from the inventive concept of this application, any known positive electrode active material, binder, or conductive material can be used in this application. Furthermore, the addition of known additives based on actual usage requirements should also be considered within the scope of protection of this application.

[0168] In some implementations, the current collector layer contains active material layers on both sides.

[0169] In some implementations, the current collector layer may be a metal foil or a composite current collector.

[0170] For example, the metal foil may be aluminum foil.

[0171] The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.

[0172] Studies have shown that traditional wet coating techniques often employ a water-based method. However, because the positive electrode active slurry is water-based, protrusions often form at the edges of the active material layer during the drying process due to the slurry's fluidity and surface tension. Furthermore, during rolling, these protrusions can directly cause cracks at the edges of the active material layer due to the rolling stress, ultimately leading to cracking of the positive electrode active material layer and affecting battery performance. Additionally, wet coating may also lead to problems such as expansion and rapid performance degradation during long-term battery cycling due to excessively high moisture content.

[0173] In some implementations, the electrode is a negative electrode.

[0174] The negative electrode sheet is formed from a lithium host material (e.g., a negative electrode active material) capable of being used as the negative terminal of a lithium-ion battery. In various aspects, the negative electrode sheet may be defined by a variety of negative electrode active material particles. Such negative electrode active material particles may be disposed in one or more layers to define the three-dimensional structure of the negative electrode. In some embodiments, the negative electrode may also include an electrolyte 50, such as a variety of electrolyte particles (not shown).

[0175] In some embodiments, the negative electrode may be a lithium-based negative electrode active material, which contains, for example, lithium metal and / or lithium alloys.

[0176] The negative electrode can be a silicon-based negative electrode active material, which includes, for example, silicon alloys, silicon oxide, or combinations thereof, and in some cases, it can also be mixed with graphite.

[0177] The negative electrode can be a carbon-based negative electrode active material, which includes one or more of graphite, graphene, carbon nanotubes (CNTs), and combinations thereof.

[0178] The negative electrode may also include one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O). 12 One or more transition metals (e.g., tin (Sn)), one or more metal oxides (e.g., vanadium oxide (V2O5), tin oxide (SnO), titanium dioxide (TiO2)), titanium niobium oxide (TixNbyOz, where 0≤x≤2, 0≤y≤24 and 0≤z≤64), metal alloys (e.g., copper-tin alloy (Cu6Sn5)), and one or more metal sulfides (e.g., iron sulfide (FeS)).

[0179] Alternatively, the negative electrode active material in the negative electrode sheet may be doped with one or more conductive materials that provide an electron conduction path and / or at least one polymer binder material that improves the structural integrity of the negative electrode. For example, the negative electrode active material may be doped with binders such as: poly(tetrafluoroethylene) (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

[0180] Conductive materials may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, SuperP, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc.

[0181] The negative electrode may include more than or equal to about 50% by weight and less than or equal to about 99% by weight of negative electrode active material, optionally more than or equal to about 0% by weight and less than or equal to about 60% by weight of solid electrolyte, optionally more than or equal to about 0% by weight and less than or equal to about 15% by weight of conductive material, and optionally more than or equal to about 0% by weight and less than or equal to about 10% by weight of binder.

[0182] In some embodiments, the solid electrolyte membrane includes a solid electrolyte and a binder.

[0183] In preparing a solid electrolyte membrane, the solid electrolyte and binder are first stirred and mixed. The mixture is then fiberized to obtain a fiberized solid electrolyte mixture. The fiberized solid electrolyte mixture is then rolled to obtain a solid electrolyte membrane.

[0184] In some embodiments, the solid electrolyte is an inorganic solid electrolyte, including one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, boride solid electrolytes, and nitride solid electrolytes.

[0185] Oxide solid electrolytes include one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, one or more garnet ceramics include, but are not limited to, Li. 6.5 La3Zr 1.75 Te 0.25 O 12 Li7La3Zr2O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La3Zr2O 12 、Li 6.75 La3Zr1.75 Nb 0.25 O 12 One or more of. One or more LISICON-type oxides include, but are not limited to, Li 14 Zn(GeO4)4, Li 3+x (P 1-x Si x )O4 (where 0 < x < 1), Li 3+x Ge x V 1-x O4 (where 0 < x < 1). One or more NASICON-type oxides can be defined by LiMM′(PO4)3, where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example, in certain variants, one or more NASICON-type oxides include, but are not limited to, Li 1+x Al x Ge 2-x (PO4)3 (LAGP) (where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4)3 (LATP) (where 0 ≤ x ≤ 2), Li 1+ x Y x Zr 2-x (PO4)3 (LYZP) (where 0 ≤ x ≤ 2), Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3. One or more perovskite-type ceramics include, but are not limited to, Li 3.3 La 0.53 TiO3, LiSr 1.65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3 (where x = 0.75y and 0.60 < y < 0.75), Li 3 / 8 Sr 7 / 16 Nb 3 / 4 Zr 1 / 4 O3, Li 3x La (2 / 3-x) TiO3 (where 0 < x < 0.25).

[0186] Sulfide solid electrolytes include, but are not limited to, Li2S-P2S5, Li2S-P2S5-MSx (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 、Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 、Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 、Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 、Li 10 SiP2S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 , (1-x) P2S 5-x One or more of Li2S (where 0.5 ≤ x ≤ 0.7).

[0187] Halogen solid electrolytes include, but are not limited to, Li₂CdC l4 Li2MgC l4 Li2Cd I4 , Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Brx One or more of (where 0 < x < 1).

[0188] The boride solid electrolyte includes, but is not limited to, one or more of Li2B4O7, Li2O-(B2O3)-(P2O5).

[0189] The nitride solid electrolyte includes, but is not limited to, one or more of Li3N, Li7PN4, LiSi2N3, LiPON.

[0190] The hydride solid electrolyte includes, but is not limited to, one or more of Li3AlH6, LiBH4, LiBH4-LiX (where X is one of Cl, Br, and I), LiNH2, Li2NH, LiBH4-LiNH2.

[0191] In some embodiments, the inorganic solid electrolyte can be one or more metal oxide particles or lithium-containing compounds, including, but not limited to, one or more of Al2O3, SiO2, TiO2, LiNbO3, Li4Ti5O4, Li3PO4.

[0192] In some embodiments, the solid electrolyte further includes a partial polymer solid electrolyte, a composite solid electrolyte composed of the polymer solid electrolyte and the inorganic solid electrolyte. In the embodiments of the present application, there is no special requirement for the mass ratio of the inorganic solid electrolyte and the polymer solid electrolyte in the composite solid electrolyte, and the user can design it according to actual needs. Among them, the polymer solid electrolyte can be at least one of polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polyethylene oxide (PEO).

[0193] In some embodiments, the polymer solid electrolyte contains a lithium salt.

[0194] In some embodiments, lithium salts include, but are not limited to, lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalate)borate (LiB(C2O4)2)(LiBOB), lithium tetrafluorooxalate phosphate (LiPF4(C2O4))(LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonylimide) (LITFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonylimide) (LiN(FSO2)2)(LIFSI), and combinations thereof. In some variations, the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonylimide) (LiTFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonylimide) (LiN(FSO2)2)(LiFSI), lithium fluoroalkylphosphonate (LiFAP), and lithium phosphate (Li3PO4).

[0195] It is understood that the terms mentioned above, including oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, nitride solid electrolytes, polymer solid electrolytes, etc., are all known in the art. The details of the above materials are merely illustrative examples and not a limitation on the scope of protection. Without departing from the inventive concept of this application, any known type of solid electrolyte can be used in this application.

[0196] In some embodiments, the thickness of the solid electrolyte membrane is 1-30 μm; preferably, it is 3-20 μm; more preferably, it is 3-15 μm.

[0197] Applying a solid electrolyte coating to the electrode surface, especially the surface of a high-capacity positive electrode, can effectively improve battery safety. However, due to limitations in energy density, the thickness of the solid electrolyte film is usually quite thin. Compared to dry-processed electrode sheets, the thickness of the solid electrolyte film is an order of magnitude smaller, which makes it prone to cracking during the dry-process composite of conductive electrode sheets.

[0198] In some embodiments, the solid electrolyte membrane is formed independently, meaning that the solid electrolyte membrane can be formed without the aid of a substrate and maintain the integrity of the membrane.

[0199] In some embodiments, the side of the solid electrolyte membrane away from the electrode sheet is covered with a substrate, the adhesion between the substrate and the solid electrolyte membrane being less than the adhesion between the solid electrolyte membrane and the electrode sheet. After rolling, at least a portion of the solid electrolyte is transferred to the electrode and separated from the substrate.

[0200] This application does not specifically limit the type of substrate. Without departing from the inventive concept of this application, any known material that provides a certain supporting function, facilitates the formation of electrolyte material film, and can be separated from the solid electrolyte membrane after rolling can be used in this application. This is merely an illustrative example and not a limitation on the scope of protection. The substrate is selected from one or more of the following: silicone oil release film, fluorine release film, PET film, PP film, PE film, PE / PP film, PP / PE / PP film, PE / PP / PE film, and non-silicone release film.

[0201] In some implementations, the electrode plates and solid electrolyte membranes may also be procured.

[0202] This application also provides a composite electrode sheet, which is prepared according to the above-described method for preparing composite electrodes.

[0203] This application also provides a lithium-ion battery comprising the composite electrode described above.

[0204] The embodiments of this application will be described in more detail below through examples. However, the embodiments of this application are not limited to these examples.

[0205] Example 1.

[0206] Through such Figure 2 The apparatus shown for preparing the composite electrode combines a positive electrode with two layers of solid electrolyte membrane, such that the solid electrolyte membrane is simultaneously bonded to both positive electrode active material layers of the positive electrode. A substrate covers the solid electrolyte membrane. The protective film is a PE-based nonwoven fabric.

[0207] The electrode sheet starts from the electrode sheet unwinding mechanism 11, passes through the first guide roller 51 to the first heating roller 71, and then is preheated by the second heating roller 72 and the third heating roller 73. After being guided by the fourth guide roller 54, it reaches the shaping roller assembly. The solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 respectively to reach the shaping roller assembly. The protective film located on both sides of the electrode sheet unwinding mechanism 11 is guided by the third guide roller 53 to reach the shaping roller assembly. Then it passes between the first shaping roller 31 and the second shaping roller 32. During the gap, under the rolling pressure of the first shaping roller 31 and the second shaping roller 32, the protective film, solid electrolyte film, electrode sheet, solid electrolyte film and protective film are rolled and laminated. Then, the protective film and substrate are guided by the fifth guide roller 55 and reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively. The protective film and substrate are separated from the composite electrode sheet to obtain the composite electrode sheet. The composite electrode sheet is guided by the sixth guide roller 56 and reaches the cooling roller 74. Then it is guided by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12 to complete the winding of the composite electrode sheet.

[0208] The prepared composite electrode has no cracks on its surface.

[0209] Example 2.

[0210] The only difference between this embodiment and Embodiment 1 is the way the downstream substrate and composite electrode are separated from the shaping roller assembly.

[0211] like Figure 3 As shown, downstream of the shaping roller assembly, the protective film is guided by the fifth guide roller 55 and reaches the protective film winding mechanism 42. The protective film winding mechanism 42 separates the protective film from the composite electrode and completes the winding. The substrate is guided by the ninth guide roller 59 and the eighth guide roller 58 and reaches the substrate winding mechanism 22. The path between the ninth guide roller 59 and the eighth guide roller 58 is a straight line. The substrate winding mechanism 22 separates the substrate from the composite electrode and completes the winding.

[0212] The prepared composite electrode has no cracks on its surface.

[0213] Example 3.

[0214] The only difference between this embodiment and Embodiment 1 is the way the downstream substrate and composite electrode are separated from the shaping roller assembly.

[0215] like Figure 4As shown, downstream of the shaping roller assembly, the protective film is guided by the fifth guide roller 55 and reaches the protective film winding mechanism 42. The protective film winding mechanism 42 separates the protective film from the composite electrode and completes the winding. The substrate is guided by the ninth guide roller 59 and the eighth guide roller 58 and reaches the substrate winding mechanism 22. The routing between the ninth guide roller 59 and the eighth guide roller 58 is an S-shaped curve. The substrate winding mechanism 22 separates the substrate from the composite electrode and completes the winding.

[0216] The prepared composite electrode has no cracks on its surface.

[0217] Example 4.

[0218] The only difference between this embodiment and Embodiment 1 is that the elastic element is an adhesive layer 81 instead of a protective film, and the adhesive layer 81 covers the outside of the first shaping roller 31 and the second shaping roller 32.

[0219] like Figure 5 As shown, the electrode sheet starts from the electrode sheet unwinding mechanism 11, passes through the first guide roller 51 to the first heating roller 71, and then is preheated by the second heating roller 72 and the third heating roller 73. After being guided by the fourth guide roller 54, it reaches the shaping roller assembly. The solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 respectively to the shaping roller assembly. Then, through the gap between the first shaping roller 31 and the second shaping roller 32, the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are rolled and laminated under the rolling pressure of the first shaping roller 31 and the second shaping roller 32. Then, the substrate is guided by the fifth guide roller 55 to the substrate winding mechanism 22. The substrate is separated from the composite electrode sheet to obtain the composite electrode sheet. The composite electrode sheet is guided by the sixth guide roller 56 to the cooling roller 74, and then by the seventh guide roller 57 to the composite electrode sheet winding mechanism 12 to complete the winding of the composite electrode sheet.

[0220] The prepared composite electrode has no cracks on its surface.

[0221] Comparative Example 1

[0222] The difference between this comparative example and Example 1 is that the composite electrode preparation device does not include a heating roller.

[0223] like Figure 6As shown, the electrode sheet starts from the electrode sheet unwinding mechanism 11 and is transported to the shaping roller assembly. The solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 respectively and then reaches the shaping roller assembly. The protective film located on both sides of the electrode sheet unwinding mechanism 11 is guided by the third guide roller 53 and then reaches the shaping roller assembly. Then, through the gap between the first shaping roller 31 and the second shaping roller 32, the protective film, solid electrolyte membrane, electrode sheet, solid electrolyte membrane and protective film are rolled and laminated under the rolling pressure of the first shaping roller 31 and the second shaping roller 32. Then, the protective film and the substrate are guided by the fifth guide roller 55 and then reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively. The protective film and the substrate are separated from the composite electrode sheet to obtain the composite electrode sheet. The composite electrode sheet is guided by the sixth guide roller 56 and then reaches the cooling roller 74. After being guided by the seventh guide roller 57, it reaches the composite electrode sheet winding mechanism 12 to complete the winding of the composite electrode sheet.

[0224] The composite electrode exhibits interlayer separation at its edges, with fine cracks present, failing to meet the usage standards for composite electrodes.

[0225] Comparative Example 2

[0226] The difference between this comparative example and Example 4 is that the composite electrode preparation device does not include a heating roller.

[0227] like Figure 7 As shown, the electrode sheet starts from the electrode sheet unwinding mechanism 11 and is transported to the shaping roller assembly. The solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 is guided by the second guide roller 52 and the third guide roller 53 respectively to the shaping roller assembly. Then, through the gap between the first shaping roller 31 and the second shaping roller 32, the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are rolled and laminated under the rolling pressure of the first shaping roller 31 and the second shaping roller 32. Then, the substrate is guided by the fifth guide roller 55 to the substrate winding mechanism 22, and the substrate is separated from the composite electrode sheet to obtain the composite electrode sheet. The composite electrode sheet is guided by the sixth guide roller 56 to the cooling roller 74, and then by the seventh guide roller 57 to the composite electrode sheet winding mechanism 12 to complete the winding of the composite electrode sheet.

[0228] The composite electrode exhibits interlayer separation at its edges, with fine cracks present, failing to meet the usage standards for composite electrodes.

[0229] Comparative Example 3.

[0230] The difference between this comparative example and Example 1 is that the composite electrode preparation device does not include a heating roller or an elastic element.

[0231] like Figure 8As shown, the electrode sheet starts from the electrode sheet unwinding mechanism 11 and is transported to the shaping roller assembly; the solid electrolyte membrane located on both sides of the electrode sheet unwinding mechanism 11 starts from the solid electrolyte membrane unwinding mechanism 21, passes through the second guide roller 52 and the third guide roller 53 and then reaches the shaping roller assembly; then, through the gap between the first shaping roller 31 and the second shaping roller 32, under the rolling pressure of the first shaping roller 31 and the second shaping roller 32, the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are composited; then the substrate is guided by the fifth guide roller 55 and reaches the substrate winding mechanism 22, the substrate winding mechanism 22 separates the substrate from the composite electrode sheet to obtain the composite electrode sheet; the composite electrode sheet is guided by the sixth guide roller 56 and then reaches the cooling roller 74, and then by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12 to complete the winding of the composite electrode sheet.

[0232] The composite electrode exhibits interlayer separation at its edges, with fine cracks present, failing to meet the usage standards for composite electrodes.

[0233] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0234] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a composite electrode, characterized in that, Includes the following steps: The electrode sheet is fed through the electrode sheet unwinding mechanism, so that the electrode sheet passes through the gap between the heating mechanism and the shaping roller assembly. The solid electrolyte membrane is conveyed through the solid electrolyte membrane unwinding mechanism located on the side of the electrode sheet unwinding mechanism, so that the solid electrolyte membrane passes through the gap between the shaping roller assembly and the electrode sheet. The electrode sheet is preheated by the heating mechanism to obtain a preheated sheet; as well as A composite electrode is prepared by roll pressing the preheated sheet and the solid electrolyte membrane together using a shaping roller assembly. The electrode sheet is prepared by a dry process to obtain a structure that is thick in the middle and thin at both sides; During the rolling process, the middle region of the electrode sheet experiences greater force than the edge region; An elastic element is provided between the shaping roller assembly and the solid electrolyte membrane; The elastic element is an adhesive layer or a protective film; the adhesive layer surrounds and covers the outside of the shaping roller assembly; the protective film is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

2. The method for preparing the composite electrode according to claim 1, characterized in that, The solid electrolyte membranes located on both sides of the electrode sheet are rolled and bonded onto the electrode sheet by the shaping roller assembly to obtain a composite electrode sheet.

3. The method for preparing the composite electrode according to claim 1, characterized in that, The electrode plate is preheated several times, with the temperature of each preheating cycle increasing progressively.

4. The method for preparing the composite electrode according to claim 1, characterized in that, The preparation method further includes cooling the composite electrode.

5. The method for preparing the composite electrode according to any one of claims 1-4, characterized in that, It also includes the following steps: Separate the substrate covering the solid electrolyte membrane from the composite electrode.

6. The method for preparing the composite electrode according to any one of claims 1-4, characterized in that, The preheating time is ≥2 seconds.

7. The method for preparing the composite electrode according to any one of claims 1-4, characterized in that, The preparation method further includes: Downstream of the shaping roller assembly, the composite electrode sheet is received by a composite electrode sheet winding mechanism. The substrate is received by the substrate winding mechanism between the shaping roller assembly and the composite electrode winding mechanism; The substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode unwinding mechanism.

8. A composite electrode, characterized in that, The composite electrode is prepared by the preparation method according to any one of claims 1-7.

9. A lithium-ion battery, characterized in that, The lithium-ion battery includes the composite electrode as described in claim 8.

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