Composite pole piece, preparation method thereof and lithium ion battery

Abstract

The invention provides a composite pole piece, a preparation method thereof and a lithium ion battery. The preparation method of the composite pole piece comprises the following steps: conveying an electrode pole piece through an electrode pole piece unwinding mechanism, so that the electrode pole piece passes through a gap between a heating mechanism and a shaping roller assembly; a solid electrolyte membrane is conveyed through a solid electrolyte membrane unwinding mechanism located on the side edge of the electrode piece unwinding mechanism, so that the solid electrolyte membrane passes through a gap between the shaping roller assembly and the electrode piece; preheating the electrode plate through a heating mechanism to obtain a preheated plate; and carrying out rolling compounding on the preheating sheet and the solid electrolyte membrane through a shaping roller assembly to prepare the composite pole piece. The composite pole piece prepared by the preparation method disclosed by the invention is good in composite effect, inconsistent in transverse compaction density and poor in transverse thickness consistency.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a composite pole piece and a preparation method thereof, and a lithium-ion battery. Background Art

[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 higher and higher. Traditionally, a solid electrolyte material layer is coated on the surface of the positive / negative electrode to improve the safety performance of the battery. However, the volatilization of the solvent in the coated solid electrolyte layer can easily cause the electrode to shrink and deform, affecting the battery performance.

[0003] Therefore, the development of dry process to prepare positive / negative electrode sheets and solid electrolyte membranes to improve the safety performance of batteries has received widespread attention. However, in the rolling step of preparing composite electrode sheets by dry process, due to the thinning treatment of the electrode sheet edge during production, when the solid electrolyte membrane is combined with the electrode sheet, it is easy to cause the electrode sheet and the solid electrolyte membrane to have poor composite effect, inconsistent lateral compaction density of the composite electrode sheet, and poor lateral thickness consistency, which will have a great impact on the safety performance and quality of lithium-ion batteries. Summary of the invention

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

[0005] A method for preparing a composite pole piece comprises 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 a 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;

[0008] Preheating the electrode plate by a heating mechanism to obtain a preheating plate; and

[0009] The preheating sheet and the solid electrolyte membrane are rolled and compounded by a shaping roller assembly to prepare a composite electrode sheet.

[0010] In some embodiments, the solid electrolyte membranes located on both sides of the electrode sheet are rolled and composited on the electrode sheet by a shaping roller assembly to obtain a composite sheet.

[0011] In some embodiments, the electrode plate is preheated several times, and the preheating temperatures are increased successively.

[0012] In some embodiments, the preheating time is ≥ 2S.

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

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

[0015] In some embodiments, the elastic member is a rubber layer, and the rubber layer surrounds and covers the outer side of the shaping roller assembly.

[0016] In some embodiments, the solid electrolyte membrane is covered with a substrate, and the method for preparing the composite electrode piece further includes the following steps: separating the substrate covered on the solid electrolyte membrane from the composite electrode piece.

[0017] In some embodiments, the method for preparing the composite pole piece further includes cooling the composite pole piece.

[0018] In some embodiments, the method for preparing the composite electrode piece further comprises:

[0019] Downstream of the shaping roller assembly, the composite pole piece is received by a composite pole piece winding mechanism;

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

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

[0022] In some embodiments, the method for preparing the composite electrode piece further comprises:

[0023] The elastic member is conveyed through 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] Between the shaping roller assembly and the substrate winding mechanism, the elastic member is received by the protective film winding mechanism.

[0025] A second aspect of the present application provides a composite pole piece, which is prepared according to the preparation method provided in the first aspect above.

[0026] A third aspect of the present application provides a lithium-ion battery, which includes the composite electrode provided in the second aspect.

[0027] The preparation method of the composite electrode sheet of the present application preheats the electrode sheet before the rolling and compounding step. The preheating temperature increases the softness of the electrode sheet, thereby improving the ductility of the electrode sheet and improving the plasticity of the electrode sheet. Therefore, when the shaping roller assembly rolls the electrode sheet and the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are more tightly engaged, thereby improving the bonding strength between the two layers of the membrane and making it easier to achieve a tight compounding effect.

[0028] In the preparation method of the composite electrode sheet of the present application, compared with the overall preheating of the electrode sheet and the solid electrolyte membrane, the rolling device for preheating the electrode sheet separately has a simpler structure and makes the preheating of the electrode sheet more sufficient. There is no need 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 preparation method of the composite pole piece of the present application, during the rolling process of the shaping roller assembly, the stress of the electrode pole piece and the solid electrolyte membrane during the rolling process is adjusted through the buffer provided by the elastic member, so that the solid electrolyte membrane can better cover the electrode pole piece; and the stress of the electrode pole piece and the solid electrolyte membrane during the rolling process is made uniform, so that the lateral thickness of the electrode pole piece after rolling tends to be consistent, avoiding the adverse effects of the rolling composite process caused by the phenomenon that the electrode pole piece is thick in the middle and thin at both ends, and avoiding the crushing of the electrode pole piece; under the joint action of the heating process and the elastic member, the degree of composite between the electrode pole piece and the solid electrolyte membrane is improved, and the consistency of the lateral thickness of the composite pole piece is improved. In addition, the composite pole piece prepared by the preparation method of the present application is applied to the battery, which helps to improve the overall safety performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Flow chart of a method for preparing a composite electrode in one embodiment of the present application.

[0032] Figure 2 This is a schematic structural diagram of a device for preparing a composite electrode according to Example 1 of the present application.

[0033] Figure 3 This is a schematic diagram of the structure of a device for preparing a composite electrode according to Example 2 of the present application.

[0034] Figure 4 This is a schematic diagram of the structure of a device for preparing a composite electrode according to Example 3 of the present application.

[0035] Figure 5 This is a schematic diagram of the structure of a device for preparing a composite electrode according to Example 4 of the present application.

[0036] Figure 6 This is a schematic structural diagram of a device for preparing a composite electrode according to comparative example 1 of the present application.

[0037] Figure 7 This is a schematic diagram of the structure of a device for preparing a composite electrode according to comparative example 2 of the present application.

[0038] Figure 8 This is a schematic diagram of the structure of a device for preparing three composite pole pieces in the comparative example of the present application.

[0039] Description of Reference Numerals

[0040] 11. Electrode pole piece unwinding mechanism; 12. Composite pole piece 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 DESCRIPTION

[0047] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

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

[0049] In the description of the present application, “plurality” means at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0050] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0051] The terms "include", "comprising", "containing", "having" or other variations herein are intended to encompass non-closed inclusions, and no distinction is made between these terms. The term "include" means that other steps and ingredients that do not affect the final result may be added. The compositions and methods / processes of the present application include, consist of, and consist essentially of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0053] See also Figure 2-5 As shown, the composite electrode sheet preparation device of the present application includes a shaping roller assembly, an electrode sheet unwinding mechanism 11, a solid electrolyte membrane unwinding mechanism 21, a heating mechanism, and a composite electrode sheet 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 sheet; 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 sheet.

[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 the electrode sheet passes through the gap between the first shaping roller 31 and the second shaping roller 32 .

[0055] It can be understood that the electrode plate of the present application is a positive electrode plate or a negative electrode plate.

[0056] The solid electrolyte membrane unwinding mechanism 21 is located upstream of the shaping roller assembly, more specifically, between the electrode sheet 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 the solid electrolyte membrane so that the solid electrolyte membrane passes 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, which are located on both sides of the electrode sheet unwinding mechanism 11, and then the solid electrolyte membrane is transported so that the two layers of solid electrolyte membrane pass through the gap between the first shaping roller 31 and the second shaping roller 32, respectively, and the electrode sheet is located between the two layers of solid electrolyte membrane.

[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 sheet unwinding mechanism 11 and the shaping roller assembly, and is used to preheat the electrode sheet and / or the solid electrolyte membrane.

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

[0061] In some embodiments, there is no particular restriction on the number of heating rollers in the composite electrode preparation device, and the specific number of heating rollers can be increased or decreased according to actual conditions.

[0062] In some embodiments, the number of the heating roller may be one, ie, the first heating roller 71 .

[0063] In some embodiments, the number of heating rollers may be multiple, and the temperature of the heating rollers gradually increases along the direction in which the electrode plate runs, so that the preheating effect is more uniform. Specifically, the heating rollers along the direction in which the electrode plate runs are the first heating roller 71, the second heating roller 72, and the third heating roller 73, wherein the number of the first heating roller 71, the second heating roller 72, and the third heating roller 73 may also be 1, 2, or more, respectively, and are not particularly limited here.

[0064] In some embodiments, the preheating time of the heating roller is ≥ 2S.

[0065] In the preparation method of the composite electrode sheet of the present application, the heating roller is used to preheat the electrode electrode sheet alone, and the solid electrolyte membrane is not preheated. The overall structure of the preparation device for preheating the electrode electrode sheet alone is relatively simple. When preheating, it is only necessary to consider whether the electrode electrode sheet is preheated sufficiently, without considering factors such as the different preheating speeds of the electrode electrode sheet, the solid electrolyte membrane, and the protective membrane, and the different preheating temperatures required.

[0066] The composite electrode sheet winding mechanism 12 is located downstream of the shaping roller assembly, and is used to provide a pulling force to the electrode sheet along the moving direction of the electrode sheet, and receive the composite electrode sheet obtained after rolling and compounding by the shaping roller assembly and complete the winding action.

[0067] It is understandable that the present application does not specifically limit the preheating method, and the preheating method can be contact preheating, blast preheating or radiation preheating to preheat the electrode plate, solid electrolyte membrane and protective film. Preferably, S-type roller contact heating is adopted, and space can be saved by rollers with large wrap angles or multiple small heating rollers. At a lower cost, rapid heating is achieved, the preheating stroke is short, the heat transfer speed is fast, and any heating roller in the contact preheating can achieve independent temperature control.

[0068] The electrode sheet is preheated before entering the shaping roller assembly. The electrode sheet after preheating will soften compared to before preheating, so that the ductility of the electrode sheet is improved; therefore, when the first shaping roller assembly rolls the solid electrolyte membrane and the electrode sheet for composite, the solid electrolyte membrane and the electrode sheet are more tightly bonded, thereby increasing the bonding strength between the two and further improving the composite effect.

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

[0070] During the production of electrode sheets, the edges of the electrode sheets are usually thinned for smooth rolling process. However, the existence of the thinned area of ​​the electrode sheets affects the fit between the solid electrolyte membrane and the electrode sheets.

[0071] Surprisingly, the preparation device of the composite electrode sheet of the present application uses the buffer provided by the elastic part during rolling, so that the solid electrolyte membrane can better cover the electrode sheet; at the same time, during the rolling process of the shaping roller assembly, the electrode sheet is thick in the middle, resulting in the force in the middle area of ​​the electrode sheet being greater than that in the edge area, and the lateral thickness of the electrode sheet tends to be consistent after rolling.

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

[0073] The yield limit of the elastic member satisfies that when the solid electrolyte membrane and the electrode plate pass through the gap in the middle of the shaping roller assembly, the solid electrolyte membrane and the electrode plate undergo plastic deformation, while the deformation of the elastic member undergoes elastic deformation.

[0074] Elastic deformation refers to the change in the relative position of points on a solid due to the action of external force. When the external force is removed, the solid returns to its original state, which is called elastic deformation.

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

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

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

[0078] The present 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, polyacrylonitrile, etc., or rubbers such as Hypalon rubber, silicone rubber, fluororubber, etc., or elastic materials such as silicone that can undergo a certain degree of deformation.

[0079] The present application does not particularly limit the thickness of the elastic member. Any necessary adjustment to the thickness of the elastic member without violating the inventive concept of the present application can be understood to be within the protection scope of the present application.

[0080] In some embodiments, the elastic member is a rubber layer 81, which surrounds and covers the outer sides of the two shaping roller assemblies.

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

[0082] Adaptively, the composite electrode preparation device of the present 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, and is arranged 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] The present application has no special requirements for the structure of the protective film. Without violating the inventive concept of the present application, any known film layer that can undergo a certain degree of elastic deformation under a certain pressure can be used in the present application. It is only used as an illustrative example, not a limitation on the scope of protection. The protective film can be selected from polymer films or non-woven fabrics. The non-woven fabrics include but are not limited to PP-based non-woven fabrics, PE-based non-woven fabrics, PET-based non-woven fabrics, PAN-based non-woven fabrics, PTFE-based non-woven fabrics, Celgard non-woven fabrics, etc. The polymer film can be selected from PVDF film, PE film, PP film, PE / PP film, PE / PP / PE film, PP / PE / PP film, PTFE film, silicone oil release film, fluorine release film, PET film, non-silicone release film, etc. It is understandable that the protective film can also be a multilayer structure composed of two or more layers of polymer films and / or non-woven fabrics.

[0084] The present application does not particularly limit the thickness of the protective film. Without violating the inventive concept of the present application, any conventional adjustment of the thickness of the protective film for adjusting the rolling effect should be deemed to be within the protection scope of the present application. It can be 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 pole piece preparation device 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 pole piece winding mechanism 12, and is used to provide tension for the protective film and to wind up the protective film.

[0086] In some embodiments, the composite pole piece preparation device further includes a substrate winding mechanism 22 .

[0087] When a substrate is provided 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 by the shaping roller assembly to obtain a composite sheet, the substrate needs to be separated. The substrate and the composite sheet are separated by providing a substrate winding mechanism 22 downstream of the shaping roller assembly. During the separation process, the substrate winding mechanism 22 provides a pulling force to the substrate covering the solid electrolyte membrane, so that the substrate is separated from the composite sheet, and the substrate winding action is completed when necessary.

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

[0089] The present application does not particularly limit the type of substrate. Without violating the inventive concept of the present application, any known material with a certain supporting effect, which can be more conducive to the film formation of the electrolyte material and can be separated from the solid electrolyte membrane after rolling can be used in the present application; it is only used as an illustrative example, not any limitation on the scope of protection, and the substrate is selected from one or more of 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 composite pole piece preparation device further includes a guide roller.

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

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

[0093] Optionally, the guide roller is located between the protective film unwinding mechanism 41 and the shaping roller assembly to provide a guiding effect for the protective film. A guide roller can also be provided between the shaping roller assembly and the protective film winding mechanism 42 to provide a guiding effect for the protective film recovery.

[0094] In some embodiments, the composite electrode preparation device further includes a cooling roller 74, which is located between the shaping roller assembly and the composite electrode winding mechanism 12, and is used to cool the composite electrode coming out of the gap of the shaping roller assembly. The present application sets a cooling roller 74 to reduce the temperature of the composite electrode, so that the composite electrode can be continuously wound, thereby improving production efficiency; at the same time, the cooling roller 74 also provides shaping for the composite electrode.

[0095] In some embodiments, the number of the cooling rollers 74 may 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 pole piece winding mechanism 12, for adjusting the cooling time of the composite pole piece.

[0097] In some embodiments, there is no particular restriction on the number of cooling rollers 74 and guide rollers in the composite electrode preparation device, and the specific number can be increased or decreased according to actual conditions.

[0098] In some embodiments, the composite electrode preparation device also includes an unwinding correction component, an electrode anti-static component, etc., which are arranged in sequence along its own unwinding route. The unwinding correction component can correct the unwinding and running routes of the electrode electrode and the solid electrolyte membrane, so that the starting material line remains at the same level. The unwinding and winding mechanism of the main material adopts a single-station correction, and the unwinding and winding of the remaining materials adopts a cantilever type, all with correction. The anti-static component performs anti-static treatment on both sides of the electrode electrode, which can reduce the friction between the electrode and the conveying roller. It can be understood that, without violating the inventive concept of the present application, in the entire process from winding, rolling, and unwinding, known functional components or structures can be used in the present application.

[0099] In some embodiments, the composite pole piece preparation apparatus further includes a tension control device.

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

[0101] In some embodiments, the tension control device includes a plurality of tension control elements disposed downstream of the sizing roller assembly, which are respectively used to control the winding tension of the composite pole piece, the substrate, and the protective film.

[0102] In some embodiments, the composite electrode preparation device further includes a thickness measuring mechanism. After the shaping roller assembly rolls and laminates, the composite electrode 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 the cooling roller 74 further include a sensor for detecting the surface temperature of the composite electrode.

[0103] In some embodiments, the tensioning force applied by the shaping roller assembly includes upper and lower rollers or a heating roller, etc., preferably a heating roller, which has a larger roller diameter and a heating device disposed 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, 800 mm, preferably 550-650 mm.

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

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

[0107] In some embodiments, the mechanical speed of the sizing 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 the higher the tape speed of the entire composite electrode preparation device, the higher the production efficiency, but too high a speed can easily lead to tape breakage of the tape-walking electrode and the solid electrolyte membrane. This application has no special requirements for the residence time of the electrode and the solid electrolyte membrane in the gap of the shaping roller assembly. On the basis of not violating the inventive concept of this application, adjustments to the residence time that do not require creative labor should be understood to fall 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 speed of the electrode sheet unwinding mechanism 11 and the linear speed of the composite electrode sheet winding mechanism 12 are also kept consistent, thereby improving the consistency of the entire composite electrode sheet rolling preparation process and improving the consistency of the composite electrode sheet.

[0110] See also Figures 2 to 5 In combination with the structure of the composite electrode preparation device, the composite electrode preparation method of the present application includes the following steps: unwinding the electrode electrode sheet through the electrode electrode sheet unwinding mechanism 11 and conveying the electrode electrode sheet to the composite electrode sheet rewinding mechanism 12, so that the electrode electrode sheet passes through the gap between the heating roller, the first shaping roller 31 and the second shaping roller 32 in sequence; conveying the solid electrolyte membrane through the solid electrolyte membrane unwinding mechanism 21 located on the side of the electrode electrode sheet unwinding mechanism 11, so that the solid electrolyte membrane passes through the gap between the shaping roller assembly and the electrode electrode sheet; then rolling and compounding through the first shaping roller 31 and the second shaping roller 32; during rolling and compounding, an elastic member is arranged 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 rewinding mechanism 12.

[0111] In some embodiments, the composite electrode sheet includes an electrode sheet and a solid electrolyte membrane located on both sides of the electrode sheet. At this time, after the electrode sheet is transported, 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 the solid electrolyte membrane is conveyed to the shaping roller assembly, so that the two layers of solid electrolyte membrane 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 two layers of solid electrolyte membrane and the electrode sheet located between the two layers of solid electrolyte membrane and the elastic member located outside the two layers of solid electrolyte membrane are bonded in pairs, and the solid electrolyte membrane is compounded on both sides of the electrode sheet under the rolling action of the shaping roller assembly; thus, a composite electrode sheet is obtained.

[0112] In some embodiments, the solid electrolyte membrane is formed independently, that is, the solid electrolyte membrane can be formed and maintain the integrity of the membrane without the aid of a substrate. At this time, after the electrode sheet and the solid electrolyte membrane enter the gap of the shaping roller assembly, a composite electrode sheet is obtained under the pressure of the shaping roller assembly, and the composite electrode sheet can be rolled up by the electrode sheet rolling mechanism.

[0113] In some embodiments, the solid electrolyte membrane is covered with a layer of substrate for providing support for the solid electrolyte membrane. When the solid electrolyte membrane unwinding mechanism 21 conveys the solid electrolyte membrane, the substrate is located on the side of the solid electrolyte membrane away from the electrode sheet. After the solid electrolyte membrane and the electrode sheet are fully composited, the substrate is separated from the composite sheet. Specifically, the substrate can be received by the substrate winding mechanism 22 located on both sides of the composite sheet winding mechanism 12, and the substrate winding mechanism 22 is between the shaping roller assembly and the composite sheet winding mechanism 12.

[0114] In some embodiments, the elastic member is a rubber layer 81, which 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 rubber layer 81 rotates with the shaping roller assembly; and when the shaping roller assembly rolls the solid electrolyte membrane and / or the electrode sheet, the rubber layer 81 provides a buffering effect on the solid electrolyte membrane and / or the electrode sheet, so that the solid electrolyte membrane can better cover one side or both sides of the electrode sheet, and at the same time, the consistency of the transverse thickness of the electrode sheet after rolling is improved.

[0115] In some embodiments, the elastic member is a rubber layer 81, and the rubber layer 81 surrounds and covers the outer side of the shaping roller assembly. Figure 5 As shown, the glue layer 81, the solid electrolyte membrane, the electrode plate, the solid electrolyte membrane and the glue layer 81 are sequentially distributed between the shaping roller assemblies. The length of the glue layer 81 along the axial direction of the shaping roller assembly can be slightly greater than the axial length of the shaping roller assembly, and the glue layer 81 rotates with the shaping roller assembly during rolling.

[0116] In some embodiments, the elastic member is a protective film, and the protective film can be unwound by two protective film unwinding mechanisms 41 located on the side of the solid electrolyte film unwinding mechanism 21 away from the electrode pole piece, and the protective film unwinding mechanism 41 conveys the protective film to the shaping roller assembly so that the two layers of protective film 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 protective film, solid electrolyte membrane, electrode pole piece, solid electrolyte membrane and protective film distributed in sequence are bonded in pairs, and the solid electrolyte membrane is compounded on both sides of the electrode pole piece under the rolling action of the shaping roller assembly; thereby a composite pole piece is obtained.

[0117] Optional, such as Figure 2-4 As shown, in the shaping roller assembly and its upstream, the electrode sheet on the electrode sheet unwinding mechanism 11 is guided by the first guide roller 51 and then reaches the first heating roller 71, and then is preheated by the second heating roller 72 and the third heating roller 73, and then guided by the fourth guide roller 54 and 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 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; thereafter, 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 membrane are first bonded upstream of the shaping roller assembly, and then contact the electrode sheet after the shaping roller assembly rotates. For example, the protective membrane is bonded to the side of the solid electrolyte membrane away from the electrode sheet at the third guide roller 53, and then the solid electrolyte membrane and the protective membrane 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 then the side of the solid electrolyte membrane away from the protective membrane contacts and bonds with the electrode sheet.

[0119] Optional, such as Figure 5 As shown, in the shaping roller assembly and its upstream, the electrode sheet on the electrode sheet unwinding mechanism 11 is guided by the first guide roller 51 and then reaches the first heating roller 71, and then is preheated by the second heating roller 72 and the third heating roller 73, and is guided by the fourth guide roller 54 and then 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 and then reaches the shaping roller assembly; the first shaping roller 31 and the second shaping roller 32 are surrounded and covered with a glue layer 81 on the outside, and the electrode sheet and the solid electrolyte membrane are composited under the rolling pressure of the first shaping roller 31 and the second shaping roller 32.

[0120] During rolling, the shaping roller assembly applies tensioning force to the electrode sheet and the solid electrolyte membrane. The protective film and the adhesive layer 81 are located between the shaping roller assembly and the solid electrolyte membrane, playing a buffering role, so that the forces applied to each site of the electrode sheet and the solid electrolyte membrane are relatively uniform. Finally, the solid electrolyte membrane in the composite sheet almost completely covers the electrode sheet, the electrode sheet and the solid electrolyte membrane are better bonded, the consistency of the lateral thickness of the composite sheet is improved, and the compaction density is also improved.

[0121] In some embodiments, the protective film and the substrate can be separated from the composite pole piece at the same time.

[0122] Optionally, downstream of the sizing roller assembly, e.g. Figure 2 As shown, the protective film, the substrate and the shaping roller assembly are bonded and separated. Specifically, 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, and 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, and then guided by the seventh guide roller 57 and reaches 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, and the substrate is separated from the composite electrode piece to obtain the composite electrode piece; the composite electrode piece is guided by the sixth guide roller 56 and then reaches the cooling roller 74, and then guided by the seventh guide roller 57 and reaches the composite electrode piece winding mechanism 12, completing the winding of the composite electrode piece.

[0124] Optionally, downstream of the shaping roller assembly, the protective film and the substrate can reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively through different guide rollers, such as Figure 3 As shown, the separation angle of the substrate and the composite electrode piece 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 line 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 piece.

[0125] Optionally, downstream of the shaping roller assembly, the protective film and the substrate can reach the protective film winding mechanism 42 and the substrate winding mechanism 22 respectively through different guide rollers, such as Figure 4As shown, the separation angle of 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 turn and then reaches the substrate winding mechanism 22, and the route 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] The present application provides a method for preparing a composite electrode sheet by using the composite electrode sheet preparation device, such as Figure 1 As shown, the following steps are included:

[0127] S10. Preheating the electrode plate;

[0128] S20. The preheated electrode sheet and the solid electrolyte membrane are rolled and composited by a shaping roller assembly to prepare a composite electrode sheet; an elastic member is provided between the shaping roller assembly and the solid electrolyte membrane.

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

[0130] See also Figure 2-4 As shown, a protective film, a solid electrolyte membrane, an electrode sheet, a solid electrolyte membrane and a protective film are sequentially distributed between the shaping roller assemblies. The protective film is transported from the upstream of the shaping roller assembly to the shaping roller assembly, passes through the gap between the shaping roller assembly and the solid electrolyte membrane and is rolled, and then continues to run downstream of the shaping roller assembly until it is recycled. Therefore, the protective film of the present application can be reused, saving production and manufacturing costs while reducing damage to the environment, and is also conducive to improving production efficiency.

[0131] In some embodiments, the elastic member is a rubber layer 81, and the rubber layer 81 surrounds and covers the outside of the shaping roller assembly.

[0132] In some embodiments, the solid electrolyte membranes located on both sides of the electrode sheet are rolled and composited on the electrode sheet by a shaping roller assembly to obtain a composite sheet.

[0133] It can be understood that in the composite electrode sheet after rolling, the solid electrolyte layer is composited on the electrode electrode sheet. The solid electrolyte membrane is located on both sides of the electrode electrode sheet, which means that both sides of the electrode electrode sheet are composited with the solid electrolyte membrane by rolling.

[0134] In some embodiments, the electrode plate is preheated several times, and the preheating temperature is gradually increased. The preheating temperature is gradually increased, so that the electrode plate is heated more evenly and the subsequent rolling and laminating is more compact.

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

[0136] In some embodiments, the preheating time of the heating roller is ≥ 2S.

[0137] In some embodiments, the side of the solid electrolyte membrane away from the electrode plate is covered with a substrate, and the method for preparing the composite plate further includes the following steps: separating the substrate from the composite plate.

[0138] In some embodiments, downstream of the shaping roller assembly, the substrate can be separated from the composite pole piece by a substrate winding mechanism 22 to rewind the substrate for recovery.

[0139] In some embodiments, the method for preparing the composite pole piece further includes the following steps: cooling the composite pole piece.

[0140] In some embodiments, a cooling roller 74 is provided to cool the composite pole piece, thereby reducing the temperature of the composite pole piece so that the composite pole piece can be continuously rolled up, thereby improving production efficiency; at the same time, the cooling roller 74 also provides shaping treatment for the composite pole piece.

[0141] In some embodiments, the method for preparing the composite electrode piece further comprises:

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

[0143] Between the shaping roller assembly and the composite pole piece 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 the composite electrode piece further comprises:

[0146] The elastic member is conveyed through a 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] Between the shaping roller assembly and the substrate winding mechanism 22 , the elastic member is received by the protective film winding mechanism 42 .

[0148] The preparation method of the composite electrode sheet of the present application preheats the electrode sheet before the rolling and compounding step. The preheating temperature increases the softness of the electrode sheet, thereby improving the ductility of the electrode sheet and improving the plasticity of the electrode sheet. Therefore, when the shaping roller assembly rolls the electrode sheet and the solid electrolyte membrane, the electrode sheet and the solid electrolyte membrane are more tightly engaged, thereby improving the bonding strength between the two layers of the membrane and making it easier to achieve a tight compounding effect.

[0149] In the preparation method of the composite electrode sheet of the present application, compared with the overall preheating of the electrode sheet and the solid electrolyte membrane, the rolling device for preheating the electrode sheet separately has a simpler structure and makes the preheating of the electrode sheet more sufficient. There is no need 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 technology, the traditional shaping roller assembly has high strength and poor deformation resistance, and the electrode plates are chamfered for the smooth rolling process, forming a structure that is thick in the middle and thin at both ends. Due to the inconsistent lateral thickness of the electrode plates, when the solid electrolyte membrane is bonded to the electrode plates, the edge area of ​​the electrode plates is still separated from the solid electrolyte membrane. When the rolling equipment rolls the electrode plates and the solid electrolyte membrane, the middle area and the edge area of ​​the electrode plates are subjected to different rolling forces of the steel roller, making it difficult for the electrode plates and the solid electrolyte membrane to be tightly compounded, that is, invalid compounding, which will cause inconsistent lateral compaction density of the composite plates, and poor consistency of the composite plates. In severe cases, the electrode plates may break, which has a great impact on the safety performance and quality of lithium-ion batteries.

[0151] The preparation method of the composite pole piece of the present application, during the rolling process of the shaping roller assembly, the stress of the electrode pole piece and the solid electrolyte membrane during the rolling process is adjusted through the buffer provided by the elastic member, so that the solid electrolyte membrane can better cover the electrode pole piece; and the stress of the electrode pole piece and the solid electrolyte membrane during the rolling process is made uniform, so that the lateral thickness of the electrode pole piece after rolling tends to be consistent, avoiding the adverse effects of the rolling composite process caused by the phenomenon that the electrode pole piece is thick in the middle and thin at both ends, and avoiding the crushing of the electrode pole piece; improving the degree of composite between the electrode pole piece, the solid electrolyte membrane and the protective film, and improving the consistency of the lateral thickness of the composite pole piece. In addition, the composite pole piece prepared by the preparation method of the present application is applied to the battery, which can effectively prevent the battery from losing powder during the charge and discharge cycle, affecting the battery's cycle performance, and helping to improve the overall safety performance of the battery.

[0152] The composite process of the present application is carried out under dry conditions, which is different from the traditional wet electrode preparation method. The traditional wet method for preparing composite electrodes is to first prepare a solid electrolyte slurry and then apply the solid electrolyte slurry to the electrode plate, or vice versa, prepare an electrode slurry and then apply the electrode slurry to the solid electrolyte membrane. No solvent is used in the preparation process of the present application, which eliminates the cumbersome drying steps in the subsequent steps and can effectively reduce production costs.

[0153] It can be understood that the dry process means that no solvent is added during the preparation of the relevant electrode plates and electrolyte membranes; the technical solutions of trace amounts of liquid lubricants or other liquid additives that may be used during the rolling process should still be within the scope of protection of this application.

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

[0157] It is understandable that the electrode plates and the solid electrolyte membrane are preferably prepared under dry conditions, so that no solvent is required during 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 adopted, the electrode sheet undergoes coating, drying and rolling processes.

[0159] In some embodiments, the electrode plate is a positive electrode plate. Positive electrode materials, especially high-nickel ternary materials with high energy density, are prone to undesirable side reactions with electrolytes, especially non-aqueous electrolytes, which cause a decrease in battery performance and potential safety hazards; a composite solid electrolyte layer on the positive electrode surface is conducive to improving the safety of the battery.

[0160] The positive electrode sheet includes an active material layer and a current collector layer. When preparing the positive electrode sheet by dry method, the active material, conductive agent and binder are first stirred to obtain a positive electrode mixture; the mixture is subjected to fiberization treatment to obtain a fiberized positive electrode mixture, and the fiberized positive electrode mixture and the current collector layer are rolled and compounded to obtain a positive electrode sheet.

[0161] In some embodiments, the fiberization method includes but is not limited to air milling, high-speed stirring, 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 of greater than or equal to about 1 μm to less than or equal to about 1,000 μm.

[0163] The positive electrode active material is one of a layered oxide, a spinel and a polyanion. For example, the layered oxide (e.g., a rock salt layered oxide) comprises one or more lithium-based positive electrode active materials selected from the following: 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 (wherein M is one of Mn, Ni, Co and Al and 0≤x≤1). The spinel comprises one or more lithium-based positive active materials selected from the group consisting of LiMn2O4 (LMO) and LiNi x Mn 1.5 O4. The olivine type contains one or more lithium-based positive electrode active materials LiMPO4 (wherein M is at least one of Fe, Ni, Co and Mn). The polyanion cation contains, for example, phosphates such as LiV2(PO4)3 and / or silicates such as LiFeSiO4.

[0164] In some embodiments, one or more lithium-based positive electrode active materials may be optionally coated (e.g., by LiNbO3 and / or Al2O3) and / or may be doped (e.g., by magnesium (Mg)). In addition, in certain embodiments, one or more lithium-based positive electrode active materials may be optionally mixed 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 positive electrode. For example, the positive electrode active material layer may contain greater than or equal to about 30 wt % to less than or equal to about 99 wt % of one or more lithium-based positive electrode active materials; greater than or equal to about 0 wt % to less than or equal to about 30 wt % of a conductive material; and greater than or equal to about 0 wt % to less than or equal to about 20 wt % of a binder.

[0165] In some embodiments, the binder includes polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butylene-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 (such as KETCHEN™ black or DENKA™ black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0167] It is understood that the above examples of positive electrode active materials, binders, and conductive materials are only illustrative, and any known positive electrode active materials, binders, and conductive materials can be used in this application without violating the inventive concept of this application. And the addition of known additives based on actual use requirements should also be considered within the scope of protection of this application.

[0168] In some embodiments, both the front and back sides of the current collector layer include active material layers.

[0169] In some embodiments, 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] Research shows that wet coating is often used in traditional technologies, but since the positive electrode active slurry is a water-based slurry, bulges often appear on the edge of the active material layer during the drying process due to the fluidity and surface tension of the slurry. At the same time, during rolling, the bulge will directly cause cracks on the edge of the active material layer due to the force of rolling, which will lead to cracking of the positive electrode active material layer, and ultimately affect the performance of the battery. In addition, wet coating also has the potential to cause expansion and rapid performance degradation during long-term battery cycling due to excessive moisture content.

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

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

[0175] In some embodiments, the negative electrode sheet may include a lithium-based negative electrode active material, which includes, for example, lithium metal and / or lithium alloy.

[0176] The negative electrode sheet may be a silicon-based negative electrode active material, which includes, for example, silicon alloy, silicon oxide, or a combination thereof, which may also be mixed with graphite in some cases.

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

[0178] The negative electrode sheet 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 a binder such as poly(tetrafluoroethylene) (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

[0180] 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, superP, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, etc.

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

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

[0183] When preparing a solid electrolyte membrane, firstly, a solid electrolyte and a binder are stirred and mixed, and the mixture is subjected to fiberization treatment to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture is rolled to obtain a solid electrolyte membrane.

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

[0185] The oxide solid electrolyte comprises 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 Ln3Z 1.75 Te 0.25 O 12 、Li7La3Zr2O 12 , Li 6.2 Ga 0.3 La 2.95 R 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 Ln3Z1.75 Nb 0.25 O 12 One or more of the following. 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 variations, 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 )PsS 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 (wherein 0.5≤x≤0.7).

[0187] Halide 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 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, the lithium salt includes, but is 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 difluorooxalatoborate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalate)borate (LiB(C2O4)2)(LiBOB), lithium tetrafluorooxalatophosphate (LiPF4(C2O4))(LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl imide) (LITFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2)(LIFSI), and combinations thereof. In certain embodiments, the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonyl imide) (LiN(FSO2)2)(LiFSI), lithium fluoroalkyl phosphonate (LiFAP), and lithium phosphate (Li3PO4).

[0195] It can be understood that the above-mentioned terms including oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, nitride solid electrolytes, polymer solid electrolytes and other materials are all known in the art. The refinement of the above-mentioned materials is only for illustrative purposes and not for limitation of the scope of protection. Without violating the inventive concept of the present application, any known type of solid electrolyte can be used in the present application.

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

[0197] Applying a solid electrolyte coating on the electrode surface, especially on the high-capacity positive electrode surface, can effectively improve the safety performance of the battery. However, due to the energy density, the thickness of the solid electrolyte membrane is usually thinner. Compared with the dry-process electrode sheet, the thickness of the solid electrolyte membrane is one order of magnitude smaller, which makes the solid electrolyte membrane easy to break when the dry-process composite conductive electrode sheet is used.

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

[0199] In some embodiments, the side of the solid electrolyte membrane away from the electrode plate is covered with a substrate, and the bonding force between the substrate and the solid electrolyte membrane is smaller than the bonding force between the solid electrolyte membrane and the electrode plate. After rolling, at least part of the solid electrolyte is transferred to the electrode and separated from the substrate.

[0200] The present application does not particularly limit the type of substrate. Without violating the inventive concept of the present application, any known material with a certain supporting effect, which can be more conducive to the film formation of the electrolyte material and can be separated from the solid electrolyte membrane after rolling can be used in the present application; it is only used as an illustrative example, not any limitation on the scope of protection, and the substrate is selected from one or more of 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 embodiments, the electrode plates and the solid electrolyte membrane may also be purchased.

[0202] The present application also provides a composite pole piece, which is prepared according to the composite pole piece preparation method provided above.

[0203] The present application further provides a lithium-ion battery, which includes the composite pole piece provided above.

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

[0205] Example 1.

[0206] Through Figure 2 The composite electrode preparation device shown in the figure composites the positive electrode with two layers of solid electrolyte membranes, so that the solid electrolyte membranes are composited on both sides of the positive electrode active material layers of the positive electrode. The solid electrolyte membrane is covered with a substrate. The protective film is a PE-based non-woven 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, and then is 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 it passes between the first shaping roller 31 and the second shaping roller 32 The gap between the protective film and the substrate is formed by the first and second shaping rollers 31 and 32, and the protective film, the solid electrolyte membrane, the electrode sheet, the solid electrolyte membrane and the protective film are rolled and composited. Then, the protective film and the 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 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 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 pole piece has no cracks on its surface.

[0209] Example 2.

[0210] The difference between this embodiment and embodiment 1 is only the method of separating the substrate and the composite pole piece downstream of 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 then reaches the protective film winding mechanism 42, and the protective film winding mechanism 42 separates the protective film from the composite electrode piece and completes the winding; 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 line between the ninth guide roller 59 and the eighth guide roller 58 is a straight line, and the substrate winding mechanism 22 separates the substrate from the composite electrode piece and completes the winding.

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

[0213] Example 3.

[0214] The difference between this embodiment and embodiment 1 is only the method of separating the substrate and the composite pole piece downstream of 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 then reaches the protective film winding mechanism 42, and the protective film winding mechanism 42 separates the protective film from the composite electrode piece and completes the winding; 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 route between the ninth guide roller 59 and the eighth guide roller 58 is an S-shaped curve, and the substrate winding mechanism 22 separates the substrate from the composite electrode piece and completes the winding.

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

[0217] Example 4.

[0218] The difference between this embodiment and the first embodiment is that the elastic member is a rubber layer 81 instead of a protective film, and the rubber layer 81 covers the outer sides 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 reach the first heating roller 71, and then is preheated by the second heating roller 72 and the third heating roller 73, and is guided by the fourth guide roller 54 to reach 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; 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 rolled and composited; then, the substrate is guided by the fifth guide roller 55 and reaches 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 and reaches the cooling roller 74, and then guided by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12, and the composite electrode sheet is wound.

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

[0221] Comparative Example 1

[0222] The difference between this comparative example and Example 1 is that no heating roller is provided in the composite electrode preparation device.

[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, under the rolling pressure of the first shaping roller 31 and the second shaping roller 32, the protective film, the solid electrolyte membrane, the electrode sheet, the solid electrolyte membrane and the protective film are rolled and composited; 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, and 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, and then guided by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12, completing the winding of the composite electrode sheet.

[0224] There is interlayer separation at the edge of the composite pole piece, and there are fine cracks at the edge, which does not meet the use standards of the composite pole piece.

[0225] Comparative Example 2

[0226] The difference between this comparative example and Example 4 is that no heating roller is provided in the composite electrode preparation device.

[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 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 rolled and composited; then the substrate is guided by the fifth guide roller 55 and reaches 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 and reaches the cooling roller 74, and then guided by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12, completing the winding of the composite electrode sheet.

[0228] There is interlayer separation at the edge of the composite pole piece, and there are fine cracks at the edge, which does not meet the use standards of the composite pole piece.

[0229] Comparative Example 3.

[0230] The difference between this comparative example and Example 1 is that no heating roller and no elastic member are provided in the composite electrode preparation device.

[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 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, and 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 reaches the cooling roller 74, and then guided by the seventh guide roller 57 and reaches the composite electrode sheet winding mechanism 12, completing the winding of the composite electrode sheet.

[0232] There is interlayer separation at the edge of the composite pole piece, and there are fine cracks at the edge, which does not meet the use standards of the composite pole piece.

[0233] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for preparing a composite pole piece, characterized in that: The following steps are involved: 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; The solid electrolyte membrane is conveyed by a solid electrolyte membrane unwinding mechanism located at 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; Preheating the electrode plate by the heating mechanism to obtain a preheating plate; and The preheating sheet and the solid electrolyte membrane are rolled and compounded by a shaping roller assembly to prepare a composite pole sheet.

2. The method for preparing a composite pole piece according to claim 1, characterized in that: The solid electrolyte membranes respectively located on both sides of the electrode plate are rolled and composited on the electrode plate by the shaping roller assembly to obtain a composite plate.

3. The method for preparing a composite pole piece according to claim 1, characterized in that: The electrode plate is preheated several times, and the preheating temperature is gradually increased.

4. The method for preparing a composite pole piece according to claim 1, characterized in that: An elastic member is arranged between the shaping roller assembly and the solid electrolyte membrane.

5. The method for preparing a composite pole piece according to claim 1, characterized in that: The preparation method also includes cooling the composite pole piece.

6. The method for preparing a composite pole piece according to any one of claims 1 to 5, characterized in that: The following steps are also included: The substrate covering the solid electrolyte membrane is separated from the composite electrode.

7. The method for preparing a composite pole piece according to any one of claims 1 to 5, characterized in that: The preheating time is ≥2S.

8. The method for preparing a composite pole piece according to any one of claims 1 to 5, characterized in that: The preparation method further comprises: Downstream of the shaping roller assembly, the composite pole piece is received by a composite pole piece winding mechanism; Between the shaping roller assembly and the composite pole piece winding mechanism, a substrate is received by a substrate winding mechanism; The substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode plate unwinding mechanism.

9. A composite pole piece, characterized in that: The composite pole piece is prepared according to the preparation method described in any one of claims 1 to 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the composite pole piece according to claim 9.

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