Preparation method and preparation device of composite pole piece and lithium ion battery

Abstract

The invention relates to a preparation method of a composite pole piece, a composite pole piece preparation device for preparing the composite pole piece and a lithium ion battery comprising the composite pole piece. The preparation method of the composite pole piece comprises the following steps: firstly, conveying an electrode pole piece through an electrode pole piece unwinding mechanism, so that the electrode pole piece passes through a gap between shaping rollers; then the 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 and the electrode piece; finally, the solid electrolyte membrane located on the side face of the electrode plate is rolled on the electrode plate through a shaping roller, and a composite electrode plate is obtained; wherein an elastic piece is arranged between the shaping roller and the solid electrolyte membrane. The composite pole piece preparation device for preparing the composite pole piece comprises a shaping roller, an electrode pole piece unwinding mechanism, a solid electrolyte membrane unwinding mechanism and an elastic piece arranged between the shaping roller and a solid electrolyte membrane.

Description

[0001] This application is application number: 202310761042.6, application date: June 27, 2023, name: Divisional application for preparation method, preparation device and lithium-ion battery of composite electrode. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a method for preparing a composite pole piece, a device for preparing the composite pole piece, and a lithium-ion battery comprising the composite pole piece. Background Art

[0003] 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 getting higher and higher. Traditional liquid batteries with non-aqueous electrolytes as electrolyte systems have many safety concerns, such as the flammability and explosion of traditional electrolyte materials, and the undesirable side reactions between positive electrode materials, especially high-energy-density high-nickel ternary materials and electrolytes, which may cause battery safety problems.

[0004] At present, the method of composite solid electrolyte on the electrode surface mainly involves coating the solid electrolyte slurry onto the electrode surface. This method can be directly embedded in the current mature coating process, but it also faces many problems. For example, (1) in the drying process after coating, due to the rapid drying and volatilization of the solvent, the surface tension of the electrode plate changes rapidly, and the electrode plate is prone to curling and warping. At the same time, the rapid volatilization of the solvent causes the crystalline binder to segregate on the surface of the plate; (2) some electrolyte materials, such as sulfide solid electrolytes, are extremely sensitive to moisture. The small amount of moisture present in the wet process can easily corrode the electrolyte material; (3) some new binders have compatibility problems with solvents, and new solvents need to be developed to adapt to the new binders; (4) the wet process consumes a large amount of solvent, and the cost of environmental governance is too high.

[0005] At present, the dry method for preparing electrode sheets has been reported. At the same time, the use of similar lamination technology to form and prepare electrodes and solid electrolyte membranes in laboratory pilot tests is known. However, the continuous production of composite electrodes before cutting is still not possible. Therefore, how to design and improve existing equipment to prepare composite electrodes is a very difficult technical problem. Summary of the invention

[0006] Based on this, the first aspect of the present invention provides a method for preparing a composite electrode sheet, which improves the consistency of the lateral thickness of the composite electrode sheet by adjusting the stress conditions of the electrode sheet and the solid electrolyte membrane during the rolling process.

[0007] A method for preparing a composite electrode sheet, comprising: conveying the electrode sheet through an electrode sheet unwinding mechanism so that the electrode sheet passes through a gap in the middle of a shaping roller; conveying a solid electrolyte membrane through a solid electrolyte membrane unwinding mechanism located on the side of the electrode sheet unwinding mechanism so that the solid electrolyte membrane passes through a gap in the middle of a shaping roller and the electrode sheet; and rolling the solid electrolyte membrane located on the side of the electrode sheet onto the electrode sheet through a shaping roller to obtain a composite electrode sheet; wherein an elastic member is provided between the shaping roller and the solid electrolyte membrane rolled onto the electrode sheet; the yield limit of the elastic member satisfies that: when the solid electrolyte membrane and the electrode sheet pass through the gap in the middle of the shaping roller, the solid electrolyte membrane and the electrode sheet undergo plastic deformation, while the elastic member undergoes elastic deformation.

[0008] 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.

[0009] The electrode plate includes a positive electrode plate and / or a negative electrode plate.

[0010] In some embodiments, the elastic member is a protective film, and the protective film is transported through a gap between a shaping roller and a solid electrolyte membrane.

[0011] In some embodiments, the elastic member is a rubber layer, and the rubber layer surrounds and covers the outer side of the shaping roller.

[0012] In some embodiments, the solid electrolyte membranes located on both sides of the electrode plate are rolled onto the electrode plate by a shaping roller to obtain a composite plate.

[0013] In some embodiments, the method further includes separating the substrate covering the solid electrolyte membrane from the composite pole piece.

[0014] In some embodiments, the protective film is a polymer film or a nonwoven fabric.

[0015] In some embodiments, the adhesive layer is plastic, rubber, or silicone.

[0016] In some embodiments, the preparation method also includes: receiving the composite pole sheet through a composite pole sheet winding mechanism downstream of the shaping roller; receiving the substrate through a substrate winding mechanism between the shaping roller and the composite pole sheet winding mechanism; the substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode pole sheet unwinding mechanism.

[0017] In some embodiments, the preparation method further includes: conveying the elastic member through a protective film unwinding mechanism; the protective film unwinding mechanism is located between the solid electrolyte membrane unwinding mechanism and the shaping roller; and receiving the elastic member through the protective film winding mechanism between the shaping roller and the substrate winding mechanism.

[0018] A second aspect of the present application provides a composite pole piece, which is obtained by the preparation method of the composite pole piece of the first aspect.

[0019] A third aspect of the present application provides a lithium-ion battery, which includes a composite pole piece prepared by the composite pole piece preparation method of the first aspect.

[0020] The fourth aspect of the present application provides a preparation device for a composite electrode sheet, which includes: shaping rollers, which include a first shaping roller and a second shaping roller; an electrode sheet unwinding mechanism, located upstream of the shaping roller, for conveying the electrode sheet so that the electrode sheet passes through the gap between the first shaping roller and the second shaping roller; and a solid electrolyte membrane unwinding mechanism, located on the side of the electrode sheet unwinding mechanism, for conveying the solid electrolyte membrane so that the solid electrolyte membrane passes through the gap between the first shaping roller and the second shaping roller; an elastic member is arranged between the shaping roller and the solid electrolyte membrane.

[0021] In some embodiments, the device also includes: a composite pole sheet winding mechanism, located downstream of the shaping roller, for receiving the composite pole sheet; and a substrate winding mechanism, between the shaping roller and the composite pole sheet winding mechanism, for receiving the substrate covered on the solid electrolyte membrane; the substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode sheet unwinding mechanism.

[0022] In some embodiments, the device also includes: a protective film unwinding mechanism, located between the solid electrolyte membrane unwinding mechanism and the shaping roller, for conveying the elastic part; and a protective film winding mechanism, located between the shaping roller and the substrate winding mechanism, for receiving the elastic part; the elastic part is a protective film.

[0023] In some embodiments, the elastic member may also be a rubber layer, which surrounds and covers the outer side of the shaping roller.

[0024] The preparation method of the composite pole piece of the present application, during the rolling process of the shaping roller, the buffer provided by the elastic member enables the solid electrolyte membrane to better cover the electrode pole piece; at the same time, during the rolling process of the shaping roller, the electrode pole piece is thick in the middle, resulting in a greater force in the middle area than in the edge area, and the lateral thickness of the electrode pole piece tends to be consistent after rolling. It avoids 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, protects the electrode pole piece from being crushed, and can also better combine the active material layer in the electrode pole piece with the solid electrolyte membrane. 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; at the same time, the present application performs rolling during the composite process of the solid electrolyte membrane and the electrode pole piece, which realizes the bulging edge phenomenon in the rolling process that needs to be solved when the electrode pole piece is edge trimmed, and avoids the influence of edge thinning on interlayer composite. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a flow chart of a method for preparing a composite electrode provided in an embodiment of the present application.

[0026] FIG. 2 is a schematic diagram of the structure of a composite pole piece before rolling provided in an embodiment of the present application.

[0027] FIG. 3 is a schematic diagram of the structure of a composite pole piece after rolling provided in an embodiment of the present application.

[0028] FIG. 4 is a schematic structural diagram of a composite electrode preparation device provided in Example 1 of the present application.

[0029] FIG. 5 is a schematic structural diagram of a composite electrode preparation device provided in Example 3 of the present application.

[0030] FIG. 6 is a schematic structural diagram of a composite electrode preparation device provided in Comparative Example 1 of the present application.

[0031] Description of Reference Numerals 1. Electrode plate; 2. Solid electrolyte membrane; 11. Electrode pole piece unwinding mechanism; 12. Composite pole piece winding mechanism; 21. Solid electrolyte membrane unwinding mechanism; 22. Substrate winding mechanism; 31. first shaping roller; 32. second shaping roller; 41. Protective film unwinding mechanism; 42. Protective film rewinding mechanism; 51. First guide roller; 52. Second guide roller; 53. Third guide roller; 54. Fourth guide roller. Implementation

[0032] 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.

[0033] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0034] In addition, if the terms "first" or "second" 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, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0038] The direction parallel to the running direction of the electrode plate is defined as the longitudinal direction, and the direction perpendicular to the running direction of the electrode plate is defined as the transverse direction.

[0039] As shown in Figures 4-5, the composite electrode sheet preparation device of the present application includes a shaping roller, an electrode sheet unwinding mechanism, a solid electrolyte membrane unwinding mechanism and a composite electrode sheet winding mechanism. The shaping roller includes a first shaping roller and a second shaping roller symmetrically arranged on both sides of the electrode sheet; the connecting line between the axes of the first shaping roller and the second shaping roller is perpendicular to the conveying direction of the electrode sheet.

[0040] The electrode sheet unwinding mechanism is located upstream of the shaping roller, 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 and the second shaping roller.

[0041] The solid electrolyte membrane unwinding mechanism is located upstream of the shaping roller, more specifically, between the electrode sheet unwinding mechanism and the shaping roller. The solid electrolyte membrane unwinding mechanism 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 and the second shaping roller. More specifically, the solid electrolyte membrane unwinding mechanism allows the solid electrolyte membrane to pass between the electrode sheet and the shaping roller.

[0042] The composite pole piece winding mechanism is located downstream of the shaping roller, and is used to provide a pulling force along the moving direction of the electrode pole piece to the electrode pole piece, and receive the composite pole piece obtained after being rolled by the shaping roller to complete the winding action.

[0043] In some embodiments, there are two solid electrolyte membrane unwinding mechanisms, which are located on both sides of the electrode sheet unwinding mechanism. The solid electrolyte membrane is then transported so that the two layers of solid electrolyte membrane pass through the gap between the first shaping roller and the second shaping roller respectively, and the electrode sheet is located between the two layers of solid electrolyte membrane.

[0044] Optionally, two solid electrolyte membrane unwinding mechanisms are symmetrically arranged on both sides of the electrode plate unwinding mechanism.

[0045] In some embodiments, the composite pole piece preparation device further includes a substrate winding mechanism.

[0046] 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 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 downstream of the shaping roller. During the separation process, the substrate winding mechanism will provide a pulling force to the substrate of the solid electrolyte membrane, so that the substrate is separated from the composite sheet, and the substrate winding action is completed when necessary.

[0047] The number of substrate winding mechanisms corresponds to the number of solid electrolyte membrane unwinding mechanisms.

[0048] In some embodiments, an elastic member is disposed between the first shaping roller and the second shaping roller.

[0049] The yield limit of the elastic member satisfies that when the solid electrolyte membrane and the electrode plate pass through the gap between the shaping rollers, the solid electrolyte membrane and the electrode plate undergo plastic deformation, while the deformation of the elastic member undergoes elastic deformation.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The present application improves the interlayer bonding force between the solid electrolyte membrane and the electrode plate membrane by means of the plastic deformation formed between the two.

[0054] It is understandable that, on the basis of meeting the above conditions, the present application has no special requirements for the rolling pressure, and the corresponding rolling pressure selected according to the different material systems should still be regarded as within the protection scope of the present application. It is only used as an illustrative example, not a limitation on the protection scope, and the rolling pressure is 10-1000 MPa.

[0055] 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.

[0056] Surprisingly, the composite electrode sheet preparation device of the present application utilizes the buffer provided by the elastic parts 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, the electrode sheet is thick in the middle, resulting in greater force in the middle area of ​​the electrode sheet than in the edge area, and the lateral thickness of the electrode sheet tends to be consistent after rolling.

[0057] In some embodiments, the thickness of the solid electrolyte membrane is 1-30 μm; preferably, 3-20 μm; more preferably, 3-15 μm.

[0058] 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.

[0059] The elastic member 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.

[0060] In some embodiments of the invention, the flexible material is a polymer.

[0061] 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.

[0062] 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.

[0063] In some embodiments, the elastic member is a rubber layer that surrounds and covers the outer sides of the two shaping rollers.

[0064] In some embodiments, the elastic member is a protective film, and the protective film is transported through the gap between the sizing roller and the solid electrolyte membrane.

[0065] Adaptively, the composite electrode sheet preparation device of the present application further includes a protective film unwinding mechanism for unwinding the protective film. The protective film unwinding mechanism is located upstream of the shaping roller and is arranged between the solid electrolyte membrane unwinding roller and the shaping roller. During the rolling composite process of the electrode sheet and the solid electrolyte membrane, the protective film is located in the gap between the shaping rollers and between the shaping rollers and the solid electrolyte membrane.

[0066] 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.

[0067] 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 multi-layer structure.

[0068] In some embodiments, the composite pole piece preparation device further comprises a protective film winding mechanism. The protective film winding mechanism is located downstream of the shaping roller, disposed between the shaping roller and the composite pole piece winding mechanism, and is used to provide tension to the protective film and receive the protective film.

[0069] In some embodiments, the composite pole piece preparation apparatus further includes a guide roller.

[0070] Optionally, the guide roller is located between the solid electrolyte membrane unwinding mechanism and the shaping roller to provide a guide for the solid electrolyte membrane. A guide roller may also be provided between the shaping roller and the substrate winding mechanism to provide a guide for the substrate of the solid electrolyte membrane separated from the composite electrode.

[0071] Optionally, the guide roller is located between the protective film unwinding mechanism and the shaping roller to provide a guiding effect for the protective film.

[0072] A guide roller can be arranged between the shaping roller and the protective film winding mechanism, and the guide roller is used to provide a guiding effect for the recovery of the protective film.

[0073] 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.

[0074] In some embodiments, the width of the shaping roller 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.

[0075] In some embodiments, the diameter of the shaping roller is 300-500 mm, including but not limited to 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, preferably 350-450 mm.

[0076] Referring to Figures 4-5, in combination with the structure of the composite electrode sheet preparation device, the composite electrode sheet preparation method of the present application includes the following steps: unwinding the electrode sheet through the electrode sheet unwinding mechanism 11 and conveying the electrode sheet to the composite electrode sheet winding mechanism 12, so that the electrode sheet passes through the gap between the first shaping roller 31 and the second shaping roller 32; conveying the solid electrolyte membrane through the 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 and the electrode sheet; then the electrode sheet and the solid electrolyte membrane are roll-compounded by the first shaping roller 31 and the second shaping roller 32; during the rolling compounding, an elastic member is arranged between the shaping roller and the solid electrolyte membrane; finally, the composite electrode sheet is received by the composite electrode sheet winding mechanism 12 downstream of the shaping roller.

[0077] In some embodiments, the composite electrode sheet includes an electrode sheet and a solid electrolyte membrane located on both sides of the electrode sheet. 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 conveyed to the shaping roller, 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 to each other, and the solid electrolyte membrane is compounded on both sides of the electrode sheet under the rolling action of the shaping roller; thus, a composite electrode sheet is obtained.

[0078] 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 between the shaping rollers, a composite electrode sheet is obtained under the pressure of the shaping rollers, and the composite electrode sheet can be rolled up by the electrode sheet rolling mechanism.

[0079] In some embodiments, the solid electrolyte membrane is covered with a substrate for providing support for the solid electrolyte membrane.

[0080] 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 completely composited, the substrate is separated from the composite sheet. Specifically, the substrate rewinding mechanism 22 located on both sides of the composite sheet rewinding mechanism 12 can receive the substrate respectively, and the substrate rewinding mechanism 22 is between the shaping roller and the composite sheet rewinding mechanism 12.

[0081] In some embodiments, the elastic member is a rubber layer, which surrounds and covers the outer sides of the first shaping roller 31 and the second shaping roller 32. When the shaping roller rotates, the rubber layer rotates with the shaping roller; and when the shaping roller rolls the solid electrolyte membrane and / or the electrode sheet, the rubber layer 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.

[0082] 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 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; thereby a composite pole piece is obtained.

[0083] Optionally, as shown in FIG4 , the solid electrolyte membrane and the protective membrane are guided by the guide roller 51 and the guide roller 52 respectively and then arrive between the first shaping roller 31 and the second shaping roller 32; the first guide roller 51 is located on the side of the second guide roller 52 away from the shaping roller. The protective membrane and the solid electrolyte membrane rotate toward the shaping roller and contact the electrode pole piece, and pass through the gap between the first shaping roller 31 and the second shaping roller 32, more specifically, through the gap between the shaping roller and the electrode pole piece. Afterwards, under the rolling pressure of the first shaping roller 31 and the second shaping roller 32, the electrode pole piece and the two layers of the solid electrolyte membrane are composited.

[0084] Optionally, the solid electrolyte membrane and the protective membrane are first bonded upstream of the shaping roller, and then contact the electrode sheet after the shaping roller rotates. For example, at the second guide roller 52, the protective membrane is bonded to the side of the solid electrolyte membrane away from the electrode sheet, 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 or the second shaping roller 32, and the side of the solid electrolyte membrane away from the protective membrane contacts and bonds with the electrode sheet.

[0085] During rolling, the shaping roller applies tensioning force to the electrode sheet and the solid electrolyte membrane, and the two layers of protective film are located between the shaping roller and the solid electrolyte membrane, which play a buffering role, so that the force on each site of the electrode sheet and the solid electrolyte membrane is 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.

[0086] In some embodiments, the protective film and the substrate can be separated from the composite pole piece at the same time.

[0087] When there is only one guide roller 53 downstream of the shaping roller, after the shaping roller is rolled, the composite electrode continues to be conveyed downstream of the shaping roller 32, and the protective film and the substrate respectively reach the third guide roller 53 after rotating along with the shaping roller under the action of the protective film winding mechanism 42 and the substrate winding mechanism 22, and then the protective film and the substrate begin to separate after rotating around the third guide roller 53 at a certain angle, the protective film moves forward to the protective film winding mechanism 42 and completes the winding action, and the substrate moves forward to the substrate winding mechanism 22 and completes the winding action.

[0088] When there are two guide rollers 53 and 54 downstream of the shaping roller, after the shaping roller is rolled, the composite electrode continues to be transported downstream of the shaping roller 32, and the protective film and the substrate are respectively rotated along with the shaping roller under the action of the protective film winding mechanism 42 and the substrate winding mechanism 22, and reach the third guide roller 53 and the fourth guide roller 54 respectively, and then the protective film moves forward to the protective film winding mechanism 42 and completes the winding action, and the substrate moves forward to the substrate winding mechanism 22 and completes the winding action.

[0089] Optionally, the guide roller 53 may be replaced by two or more guide rollers; the guide roller 54 may be replaced by two or more guide rollers.

[0090] In some embodiments, the protective film may also be separated from the composite electrode sheet before the substrate. After the shaping roller is rolled, the composite electrode sheet continues to be conveyed downstream of the shaping roller 32. Under the action of the protective film winding mechanism 42, the protective film rotates with the shaping roller and reaches the third guide roller 53. After the protective film rotates around the third guide roller 53 for a certain angle, it continues to move forward to the protective film winding mechanism 42 and completes the winding action. After the substrate leaves the shaping roller and is conveyed with the composite electrode sheet for a certain distance, the substrate is separated from the composite electrode sheet under the action of the substrate winding mechanism 22 and reaches the fourth guide roller 54. After the substrate rotates around the fourth guide roller 54 for a certain angle, it continues to move forward to the protective film winding mechanism 42 and completes the winding action.

[0091] In some embodiments, the solid electrolyte membrane can be guided from the solid electrolyte membrane unwinding mechanism to the shaping roller via the guide roller, and the number of guide rollers includes but is not limited to 1, 2, 3, 4, 5 or more. The specific number can be increased or decreased according to actual conditions, and 1 or 2 guide rollers are preferred.

[0092] When the substrate of the solid electrolyte membrane is recovered, it can be guided and transmitted to the substrate winding mechanism through guide rollers, and the number of guide rollers includes but is not limited to 1, 2, 3, 4, 5 or more, preferably 1 guide roller.

[0093] The protective film may be guided from the protective film winding mechanism to the shaping roller via guide rollers, and the number of guide rollers includes but is not limited to 1, 2, 3, 4, 5 or more, preferably 1 or 2 guide rollers.

[0094] When the protective film is recovered, it can be guided and transmitted to the protective film winding mechanism through guide rollers. The number of guide rollers includes but is not limited to 1, 2, 3, 4, 5 or more, preferably 1 or 2 guide rollers.

[0095] Optionally, in the process of conveying the solid electrolyte membrane and the protective membrane to the shaping roller, part or all of the guide rollers may be used in common.

[0096] In some embodiments, the mechanical speed of the sizing roller is 5-60 m / min, including but not limited to 5 m / min, 10 m / min, 20 m / min, 30 m / min, 40 m / min, 45 m / min, 50 m / min, 60 m / min.

[0097] 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 problems such as 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 between the shaping rollers. On the basis of not violating the inventive concept of this application, any adjustment to the residence time that does not require creative labor should be understood to fall within the scope of protection of this application.

[0098] In some embodiments, the linear speeds of the first shaping roller and the second shaping roller are kept consistent, and the linear speeds of the electrode sheet unwinding mechanism and the linear speed of the composite sheet winding mechanism are also kept consistent, thereby improving the consistency of the entire composite sheet rolling preparation process and the consistency of the composite sheet.

[0099] In some embodiments, the linear speeds of the first shaping roller and the second shaping roller are inconsistent. The rolling effect is adjusted by setting the first shaping roller and the second shaping roller at different speeds.

[0100] In some embodiments, a heating unit is disposed inside the shaping roller, and the temperature of the heating shaping roller is in the range of 100-300°C, including but not limited to 100°C, 150°C, 200°C, 250°C, 300°C, preferably 150-200°C.

[0101] Refer to FIG1 , which shows a flow chart of the method for preparing a composite electrode sheet using the composite electrode sheet preparation device of the present invention. First, the solid electrolyte membrane is positioned on one side or both sides of the electrode electrode sheet respectively, and then the electrode electrode sheet and the solid electrolyte membrane are continuously passed through the gap between the sizing rollers under dry conditions, and the composite electrode sheet is obtained after rolling under the action of the elastic member. The elastic member is used to adjust the force of the electrode electrode sheet and the solid electrolyte membrane during the rolling process, so that the solid electrolyte membrane can better cover the electrode electrode sheet; and the lateral thickness of the electrode electrode sheet tends to be consistent after rolling.

[0102] 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.

[0103] In some embodiments, the elastic member is a protective film. The protective film is arranged in the gap between the shaping roller and the solid electrolyte membrane during rolling. As shown in Figures 4-5, a protective film, a solid electrolyte membrane, an electrode sheet, a solid electrolyte membrane and a protective film are sequentially distributed between the shaping rollers. The protective film starts from the upstream of the shaping roller and arrives at the shaping roller after transportation. After passing through the gap between the shaping roller and the solid electrolyte membrane and being rolled, it continues to run downstream of the shaping roller until it is recycled. Therefore, the protective film of the present application can be reused repeatedly, which saves production and manufacturing costs while reducing damage to the environment, and is also conducive to improving production efficiency.

[0104] In some embodiments, the protective film may be recovered downstream of the sizing roller by separating the protective film from the composite pole piece.

[0105] In some embodiments, the elastic member is a rubber layer, which surrounds and covers the outer side of the shaping roller. As shown in FIG5 , the rubber layer, the solid electrolyte membrane, the electrode sheet, the solid electrolyte membrane and the rubber layer are sequentially distributed between the shaping rollers. The length of the rubber layer along the axial direction of the shaping roller can be slightly greater than the axial length of the shaping roller, and the rubber layer rotates with the shaping roller during rolling.

[0106] 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.

[0107] 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.

[0108] In some embodiments, the electrode plates and the solid electrolyte membrane are both prepared by a dry process.

[0109] In some embodiments, at least one of the electrode sheet and the solid electrolyte membrane is prepared by a dry process.

[0110] In some embodiments, the electrode plates and the solid electrolyte membrane are both prepared by a wet process.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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, the conductive agent and the binder are first stirred to obtain a positive electrode mixture; the mixture is subjected to a 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. In some embodiments, the fiberization method includes but is not limited to airflow milling, high-speed stirring, mechanical fusion, twin-screw extrusion, etc.

[0115] 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.

[0116] 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) contains one or more lithium-based positive electrode active materials selected from the following: LiCoO2 (LCO), LiNixMnyCo1-x-yO2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi1-x-yCoxAlyO2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNixMn1-xO2 (where 0 ≤ x ≤ 1), and Li1+xMO2 (where M is one of Mn, Ni, Co and Al and 0 ≤ x ≤ 1). The spinel contains one or more lithium-based positive electrode active materials selected from the following: LiMn2O4 (LMO) and LiNixMn1.5O4. The olivine type includes 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 includes, for example, phosphates such as LiV2(PO4)3 and / or silicates such as LiFeSiO4.

[0117] 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 include 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 the conductive material; and greater than or equal to about 0 wt% to less than or equal to about 20 wt% of the binder.

[0118] 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.

[0119] 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 KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0120] 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.

[0121] In some embodiments, both the front and back sides of the current collector layer include active material layers.

[0122] In some embodiments, the current collector layer may be a metal foil or a composite current collector.

[0123] For example, the metal foil may be aluminum foil.

[0124] 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.

[0125] 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.

[0126] In some embodiments, the electrode plate is a negative electrode plate.

[0127] The negative electrode sheet is formed of a lithium-based 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 a 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).

[0128] 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.

[0129] 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.

[0130] 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.

[0131] The negative electrode sheet may also include one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O12), one or more transition metals (such as tin (Sn)), one or more metal oxides (such as 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 (such as copper tin alloy (Cu6Sn5)) and one or more metal sulfides (such as iron sulfide (FeS)).

[0132] Alternatively, the negative electrode active material in the negative electrode sheet may be doped with one or more conductive materials that provide an electronic 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 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. The conductive material may include carbon-based materials, powdered nickel or other metal particles or conductive polymers. The carbon-based material may include particles such as carbon black, graphite, superP, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, and the like. Examples of the conductive polymer include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, and the like.

[0133] The negative electrode sheet may include greater than or equal to about 50 wt % to less than or equal to about 99 wt % of a negative electrode active material, optionally greater than or equal to about 0 wt % to less than or equal to about 60 wt % of a solid electrolyte, optionally greater than or equal to about 0 wt % to less than or equal to about 15 wt % of a conductive material, and optionally greater than or equal to about 0 wt % to less than or equal to about 10 wt % of a binder.

[0134] Dry preparation As mentioned in the background technology, due to the high strength and poor deformation resistance of the traditional shaping roller, the electrode plate is chamfered for the smooth rolling process, forming a structure with thick middle and thin ends. As shown in Figure 2, due to the inconsistent lateral thickness of the electrode plate 1, when the solid electrolyte membrane 2 is attached to the electrode plate 1, the edge area of ​​the electrode plate 1 is still separated from the solid electrolyte membrane. When the rolling equipment rolls the electrode plate 1 and the solid electrolyte membrane 2, the middle area and the edge area of ​​the electrode plate 1 are subjected to different rolling forces of the steel roller, making it difficult for the electrode plate 1 and the solid electrolyte membrane 2 to be tightly compounded, that is, invalid compounding, which will cause inconsistent lateral compaction density of the composite plate, and poor consistency of the composite plate. In severe cases, the electrode plate may be broken, which has a great impact on the safety performance and quality of lithium-ion batteries.

[0135] The preparation method of the present application utilizes the buffer provided by the elastic member during the rolling of the shaping roller, so that the solid electrolyte membrane can better cover the electrode sheet; at the same time, during the rolling process of the shaping roller, the electrode sheet is thick in the middle, resulting in a greater force in the middle area of ​​the electrode sheet than in the edge area. After rolling, the lateral thickness of the electrode sheet tends to be consistent as shown in Figure 3, which is effective compounding. This avoids the adverse effects of the rolling compounding process caused by the phenomenon that the electrode sheet 1 is thick in the middle and thin at both ends, protects the electrode sheet 2 from being crushed, and can also make the active material layer in the electrode sheet 1 and the solid electrolyte membrane 2 better combined. In addition, during the rolling process of the shaping roller, the electrode sheet 1 and the solid electrolyte membrane 2 can be pressed evenly under force, which improves the compaction density of the composite sheet, ensures the consistency of the thickness of the composite sheet, weakens the phenomenon that the electrode sheet 1 is thick in the middle and thin at both ends, improves the quality of continuous rolling, and can be used for large-scale production.

[0136] In some embodiments, a solid electrolyte membrane includes a solid electrolyte and a binder.

[0137] 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.

[0138] 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.

[0139] 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, one or more of Li6.5La3Zr1.75Te0.25O12, Li7La3Zr2O12, Li6.2Ga0.3La2.95Rb0.05Zr2O12, Li6.85La2.9Ca0.1Zr1.75Nb0.25O12, Li6.25Al0.25La3Zr2O12, Li6.75La3Zr1.75Nb0.25O12. One or more LISICON-type oxides include, but are not limited to, one or more of Li14Zn(GeO4)4, Li3+x(P1 xSix)O4 (where 0 < x < 1), Li3+xGexV1-xO4 (where 0 < x < 1). One or more NASICON-type oxides can be defined by LiMM (PO4)3, where M and Mʹ 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, one or more of Li1+xAlxGe2-x(PO4)3 (LAGP) (where 0 ≤ x ≤ 2), Li1+xAlxTi2-x(PO4)3 (LATP) (where 0 ≤ x ≤ 2), Li1+xYxZr2-x(PO4)3 (LYZP) (where 0 ≤ x ≤ 2), Li1.3Al0.3Ti1.7(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, one or more of Li3.3La0.53TiO3, LiSr1.65Zr1.3Ta1.7O9, Li2x-ySr1-xTayZr1-yO3 (where x = 0.75y and 0.60 < y < 0.75), Li3 / 8Sr7 / 16Nb3 / 4Zr1 / 4O3, Li3xLa(2 / 3-x)TiO3 (where 0 < x < 0.25).

[0140] Sulfide solid electrolytes include, but are not limited to, one or more of Li2S-P2S5, Li2S-P2S5-MSx (where M is Si, Ge, and Sn and 0≤x≤2), Li3.4Si0.4P0.6S4, Li10GeP2S11.7O0.3, Li9.6P3S12, Li7P3S11, Li9P3S9O3, Li10.35Si1.35P1.65S12, Li9.81Sn0.81P2.19S12, Li10(Si0.5Ge0.5)P2S12, Li(Ge0.5Sn0.5)P2S12, Li(Si0.5Sn0.5)PsS12, Li10GeP2S12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li10.35Ge1.35P1.65S12, Li3.25Ge0.25P0.75S4, Li10SnP2S12, Li10SiP2S12, Li9.54Si1.74P1.44S11.7Cl0.3, (1-x)P2S5-xLi2S (where 0.5≤x≤0.7).

[0141] Halide solid electrolytes include, but are not limited to, one or more of Li2CdCl4, Li2MgCl4, Li2CdI4, Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl1-xBrx (where 0<x<1).

[0142] Boride solid electrolytes include, but are not limited to, one or more of Li2B4O7, Li2O-(B2O3)-(P2O5).

[0143] Nitride solid electrolytes include, but are not limited to, one or more of Li3N, Li7PN4, LiSi2N3, LiPON.

[0144] Hydride solid electrolytes include, but are not limited to, one or more of Li3AlH6, LiBH4, LiBH4-LiX (where X is one of Cl, Br, and I), LiNH2, Li2NH, LiBH4-LiNH2.

[0145] 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.

[0146] In some embodiments, the solid electrolyte further includes a partial polymer solid electrolyte.

[0147] Composite solid electrolyte composed of polymer solid electrolyte and inorganic solid electrolyte. In the embodiment of the present application, there is no special requirement for the mass ratio of inorganic solid electrolyte and 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).

[0148] In some embodiments, the polymer solid electrolyte includes a lithium salt.

[0149] 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 variations, 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).

[0150] 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.

[0151] 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.

[0152] 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.

[0153] The present application does not particularly limit the type of substrate. Without violating the inventive concept of the present application, any known material that has a certain supporting effect, 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.

[0154] The present application also provides a composite pole piece, which is prepared according to the composite pole piece preparation method provided above.

[0155] The present application further provides a lithium-ion battery, which includes the composite pole piece provided above.

[0156] In some embodiments, the electrode plates and the solid electrolyte membrane may also be purchased.

[0157] Hereinafter, the embodiments of the present invention will be described in more detail by way of examples. However, the embodiments of the present invention are not limited only to these examples.

[0158] Example 1 1. Preparation of positive electrode Lithium manganate is selected as the positive electrode active material, Ketjen black is selected as the conductive agent and PTFE is selected as the binder. The above substances are mixed and stirred using a high-speed stirrer to obtain a positive electrode mixture. The mixture is then subjected to a fiberization treatment by air jet milling to obtain a fiberized mixture of the positive electrode, i.e., a positive electrode active material layer. The positive electrode active material layer is compounded with a current collector by roller pressing to obtain a positive electrode sheet.

[0159] 2. Preparation of solid electrolyte membrane LATP was selected as the solid electrolyte and polytetrafluoroethylene was selected as the binder. The above substances were mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. The mixture was then subjected to a fiberization treatment by air jet milling to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture was subjected to roller pressing to obtain a solid electrolyte membrane.

[0160] 3. Preparation of composite positive electrode sheet The positive electrode sheet is composited with two layers of solid electrolyte membranes by using a composite electrode sheet preparation device provided with a protective film as shown in FIG4 , so that the solid electrolyte membranes are composited on both sides of the positive electrode active material layers of the positive electrode sheet at the same time. The protective film is a PE-based non-woven fabric.

[0161] The solid electrolyte membrane starts from the solid electrolyte membrane unwinding mechanism 21, passes through the first guide roller 51 and reaches the shaping roller; the protective film starts from the protective film unwinding mechanism, passes through the second guide roller 52 and reaches the shaping roller; the first guide roller 51 is located on the side of the second guide roller 52 away from the shaping roller. The solid electrolyte membrane and the protective film contact the positive electrode sheet after rotating with the shaping roller, and pass through the gap between the first shaping roller and the second shaping roller, more specifically, through the gap between the shaping roller and the positive electrode sheet. After that, under the rolling pressure of the first shaping roller and the second shaping roller, the positive electrode sheet and the two layers of solid electrolyte membrane are composited. Under the action of the composite electrode sheet rewinding mechanism 12, the composite electrode sheet advances to the composite electrode sheet rewinding mechanism 12, and is received and rewound by the composite electrode sheet rewinding mechanism 12, so as to obtain a composite electrode sheet with solid electrolyte membrane composited on both sides of the positive electrode sheet.

[0162] After the protective film and the substrate leave the gap between the first shaping roller 31 and the second shaping roller 32, the protective film and the substrate are separated from the composite electrode sheet and rotate a certain angle with the first shaping roller 31 or the second shaping roller 32. The protective film is received and rolled up by the protective film winding mechanism via the third guide roller 53; the substrate is received and rolled up by the solid electrolyte membrane winding mechanism via the fourth guide roller 54; the third guide roller 53 is located on the side of the fourth guide roller 52 close to the shaping roller.

[0163] The thickness of the middle area of ​​the composite pole piece was detected to be 160μm, and the thickness of the edge area was 160μm. There were no cracks on the surface of the composite pole piece when observed with the naked eye, which met the use standards of the composite pole piece; the protective film did not undergo obvious deformation.

[0164] Example 2 1. Preparation of positive electrode Lithium manganate is selected as the positive electrode active material, Ketjen black is selected as the conductive agent and PTFE is selected as the binder. The above substances are mixed and stirred using a high-speed stirrer to obtain a positive electrode mixture. The mixture is then subjected to a fiberization treatment by air jet milling to obtain a fiberized mixture of the positive electrode, i.e., a positive electrode active material layer. The positive electrode active material layer is compounded with a current collector by roller pressing to obtain a positive electrode sheet.

[0165] 2. Preparation of solid electrolyte membrane LGPS was selected as the solid electrolyte, polytetrafluoroethylene as the binder and LiPF6 as the lithium salt, and the above substances were mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. The mixture was then fiberized by air jet milling to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture was rolled to obtain a solid electrolyte membrane.

[0166] 3. Preparation of composite positive electrode sheet The positive electrode sheet and the two layers of solid electrolyte membrane are compounded by a composite electrode sheet preparation device provided with a protective film, so that the solid electrolyte membrane is compounded on the positive electrode active material layers on both sides of the positive electrode sheet at the same time. The protective film is a PE-based non-woven fabric. The solid electrolyte membrane starts from the solid electrolyte membrane unwinding mechanism, passes through the first guide roller and the second guide roller, and reaches the shaping roller; the protective film starts from the protective film unwinding mechanism, passes through the second guide roller 52 and reaches the shaping roller; the first guide roller 51 is located on the side of the second guide roller 52 away from the shaping roller. The solid electrolyte membrane and the protective film contact the positive electrode sheet after rotating with the shaping roller, and pass through the gap between the first shaping roller and the second shaping roller, more specifically, through the gap between the shaping roller and the positive electrode sheet. After that, under the rolling pressure of the first shaping roller and the second shaping roller, the positive electrode sheet and the two layers of solid electrolyte membrane are compounded. The composite electrode sheet moves toward the composite electrode sheet winding mechanism under the action of the composite electrode sheet winding mechanism, and is received and wound by the composite electrode sheet winding mechanism 12, thereby obtaining a composite electrode sheet having solid electrolyte membranes on both sides of the positive electrode sheet.

[0167] After the protective film and the substrate leave the gap between the first shaping roller and the second shaping roller, the protective film and the substrate are separated from the composite electrode piece and rotate a certain angle with the first shaping roller or the second shaping roller. Then, the protective film and the substrate are respectively conveyed to the third guide roller under the action of the protective film winding mechanism and the substrate winding mechanism 22, and the protective film and the substrate are separated after rotating around the third guide roller for a certain angle. The protective film is received and wound by the protective film winding mechanism 42, and the substrate is received and wound by the substrate winding mechanism 22.

[0168] The thickness of the middle area of ​​the composite pole piece was detected to be 190μm, and the thickness of the edge area was 190μm. There were no cracks on the surface of the composite pole piece when observed with the naked eye, which met the use standards of the composite pole piece; the protective film did not undergo obvious deformation.

[0169] Example 3 1. Preparation of positive electrode Lithium manganate is selected as the positive electrode active material, Ketjen black is selected as the conductive agent and PTFE is selected as the binder. The above materials are mixed and stirred using a high-speed stirrer to obtain a positive electrode mixture. The mixture is then subjected to a fiberization treatment by air jet milling to obtain a fiberized mixture of the positive electrode, i.e., a positive electrode active material layer. The positive electrode active material layer is compounded with a current collector by roller pressing to obtain a positive electrode sheet.

[0170] 2. Preparation of solid electrolyte membrane LATP was selected as the solid electrolyte and polytetrafluoroethylene was selected as the binder. The above substances were mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. The mixture was then subjected to a fiberization treatment by air jet milling to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture was subjected to roller pressing to obtain a solid electrolyte membrane.

[0171] 3. Preparation of composite positive electrode sheet The positive electrode sheet and the two layers of solid electrolyte membrane are compounded by a roller press provided with a glue layer as shown in FIG. 5 , so that the solid electrolyte membrane is compounded on the positive electrode active material layers on both sides of the positive electrode sheet at the same time.

[0172] The solid electrolyte membrane starts from the solid electrolyte membrane unwinding mechanism, passes through the first guide roller and reaches the shaping roller; the solid electrolyte membrane contacts the positive electrode sheet after rotating with the shaping roller, and passes through the gap between the first shaping roller and the second shaping roller. The composite electrode sheet moves toward the composite electrode sheet winding mechanism 12 under the action of the composite electrode sheet winding mechanism 12, and is received and wound by the composite electrode sheet winding mechanism 12, so as to obtain a composite electrode sheet with solid electrolyte membrane on both sides of the positive electrode sheet. After the substrate leaves the gap between the first shaping roller 31 and the second shaping roller 32, the substrate rotates a certain angle with the first shaping roller 31 or the second shaping roller 32, and then the substrate is conveyed to the third guide roller 53 under the action of the substrate winding mechanism 22, and is received and wound by the substrate winding mechanism 22 located downstream of the third guide roller 53.

[0173] The thickness of the middle area of ​​the composite pole piece was detected to be 160μm, and the thickness of the edge area was 160μm. There were no cracks on the surface of the composite pole piece when observed with the naked eye, which met the use standards of the composite pole piece; the appearance of the glue layer remained good.

[0174] Comparative Example 1 The positive electrode sheet and the two layers of solid electrolyte membrane are composited by using a roller press as shown in FIG6 , so that the solid electrolyte membrane is composited on both sides of the positive electrode active material layer of the positive electrode sheet at the same time; the roller press shown in FIG6 differs from the roller press shown in FIG5 in that there is no glue layer on the outside of the shaping roller. The methods for preparing the positive electrode sheet, preparing the solid electrolyte membrane and preparing the composite positive electrode sheet are all consistent with those in Example 3.

[0175] There is interlayer separation at the edge of the composite pole piece, and there are fine cracks at the edge.

[0176] 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.

[0177] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0178] Therefore, the protection scope of the patent for this invention shall be based on the attached claims.

Claims

1. A method for preparing a composite pole piece, characterized in that: include: The electrode sheet is conveyed by the electrode sheet unwinding mechanism so that the electrode sheet passes through the gap between the shaping rollers; 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 and the electrode sheet; as well as The solid electrolyte membrane located on the side of the electrode sheet is rolled onto the electrode sheet by a shaping roller to obtain a composite electrode sheet; Wherein, an elastic member is arranged between the shaping roller and the solid electrolyte membrane rolled on the electrode plate; the yield limit of the elastic member satisfies: when the solid electrolyte membrane and the electrode plate pass through the gap between the shaping rollers, the solid electrolyte membrane and the electrode plate undergo plastic deformation, and the elastic member undergoes elastic deformation; The electrode plates include positive electrode plates and / or negative electrode plates.

2. The method according to claim 1, characterized in that The elastic member is a protective film, and the protective film is transported through a gap between the shaping roller and the solid electrolyte membrane.

3. The method according to claim 1, characterized in that The elastic member is a rubber layer, and the rubber layer surrounds and covers the outer side of the shaping roller.

4. The method according to claim 1, characterized in that The solid electrolyte membranes located on both sides of the electrode pole piece are rolled onto the electrode pole piece by a shaping roller to obtain a composite pole piece.

5. The method according to any one of claims 1 to 4, characterized in that: The method further comprises: separating the substrate covering the solid electrolyte membrane from the composite pole piece.

6. The method according to claim 2, characterized in that: The protective film is a polymer film or a non-woven fabric.

7. The method according to claim 3, characterized in that: The adhesive layer is made of plastic, rubber, or silicone.

8. The method according to claim 1, characterized in that The preparation method further comprises: Downstream of the shaping roller, receiving the composite pole piece through a composite pole piece winding mechanism; Between the shaping roller 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. The method according to claim 8, characterized in that The preparation method further comprises: The elastic member is conveyed by a protective film unwinding mechanism; the protective film unwinding mechanism is located between the solid electrolyte membrane unwinding mechanism and the shaping roller; and The elastic member is received by a protective film winding mechanism between the shaping roller and the substrate winding mechanism.

10. A composite pole piece, characterized in that: The composite electrode is prepared by the method according to any one of claims 1 to 9.

11. A lithium ion battery, characterized in that: The composite electrode is prepared by the method according to any one of claims 1 to 9.

12. A composite pole piece preparation device, used for preparing a composite pole piece, characterized in that: The device comprises: The shaping rollers include a first shaping roller and a second shaping roller; an electrode sheet unwinding mechanism, located upstream of the shaping roller, for conveying the electrode sheet so that the electrode sheet passes through the gap between the first shaping roller and the second shaping roller; and A solid electrolyte membrane unwinding mechanism, located at the side of the electrode sheet unwinding mechanism, used for conveying the solid electrolyte membrane so that the solid electrolyte membrane passes through the gap between the first shaping roller and the second shaping roller; An elastic member is arranged between the shaping roller and the solid electrolyte membrane.

13. The device according to claim 12, characterized in that The device also includes: A composite pole piece winding mechanism, located downstream of the shaping roller, for receiving the composite pole piece; and The substrate winding mechanism is between the shaping roller and the composite electrode sheet winding mechanism, and is used to receive the substrate covered on the solid electrolyte membrane; the substrate winding mechanism and the solid electrolyte membrane unwinding mechanism are located on the same side of the electrode sheet unwinding mechanism.

14. The device according to claim 13, characterized in that The device also includes: A protective film unwinding mechanism, located between the solid electrolyte membrane unwinding mechanism and the shaping roller, and used for conveying the elastic member; as well as A protective film winding mechanism, located between the shaping roller and the substrate winding mechanism, and used for receiving the elastic member; The elastic member is a protective film.

15. The device according to claim 12 or 13, characterized in that The elastic member is a rubber layer, and the rubber layer surrounds and covers the outer side of the shaping roller.

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