Composite pole piece, preparation method thereof and lithium ion battery

Abstract

The invention relates to a preparation method of a composite pole piece. The preparation method comprises the following steps: heating an electrode pole piece and a first solid electrolyte membrane through a first heater; compounding the heated electrode plate and the first solid electrolyte membrane through a first shaping roller assembly to obtain a composite membrane; heating the composite membrane and the second solid electrolyte membrane through a second heater; and compounding the heated composite membrane and a second solid electrolyte membrane through a second shaping roller assembly to obtain the composite pole piece, at least one of the first shaping roller assembly and the second shaping roller assembly is an elastic rolling assembly. According to the method, the compounding effect between the solid electrolyte membrane and the electrode pole piece is improved through the heating procedure, and the thickness consistency of the rolled composite pole piece is improved through the elastic rolling assembly in the preparation process.

Description

[0001] This application is application number: 202310847662.1, application date: July 12, 2023, name: Divisional application for composite pole piece and preparation method thereof, and lithium-ion battery. 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 composite pole piece prepared by the method, and a lithium-ion battery comprising the composite pole piece. Background Art

[0003] With the development of battery technology, the demand for batteries and safety performance are becoming increasingly higher. Studies have shown that coating a layer of solid electrolyte material on the electrode plate can help improve the safety of the battery. At present, the wet process is usually used to coat the solid electrolyte on the positive electrode surface, that is, the raw materials of the solid electrolyte membrane are dissolved in an organic solvent and applied to the positive electrode surface by coating, but the wet coating process has a series of defects. For example, in the subsequent drying process, due to the rapid volatilization of the solvent, the surface tension of the liquid is affected, and the wet coating will produce bulges on the edge after drying, which is easy to crack during subsequent rolling; for example, the use of a large amount of solvent in the wet process will cause environmental pollution. In recent years, dry electrode technology has emerged to solve these problems. In addition, because the dry process does not require solvent recovery and other equipment, it can also reduce production costs. Dry preparation of electrodes has received widespread attention, but there are currently no reports on dry preparation of composite pole pieces.

[0004] Compared with dry electrodes, the difficulty in preparing composite electrodes containing solid electrolyte membranes through dry processes is that the dry rolling composite of multi-layer structures has different technical characteristics from the rolling of single-layer structures; on the other hand, the bonding strength between the two layers of dry membranes still needs to be improved; therefore, it is very important to study a preparation method for dry composite electrodes with universal applicability. Summary of the invention

[0005] Based on this, it is necessary to provide a method for preparing a composite electrode, the preparation method comprising: The electrode sheet is conveyed by the electrode sheet unwinding mechanism so that the electrode sheet passes through the first heater; The first solid electrolyte membrane is conveyed by a first solid electrolyte membrane unwinding mechanism located on one side of the electrode sheet unwinding mechanism, so that the first solid electrolyte membrane passes through a first heater; Heating the electrode plate and the first solid electrolyte membrane by a first heater; Compounding the heated electrode sheet and the first solid electrolyte membrane by a first shaping roller assembly to obtain a composite membrane sheet; The second solid electrolyte membrane is conveyed by a second solid electrolyte membrane unwinding mechanism located on the other side of the electrode sheet unwinding mechanism, so that the second solid electrolyte membrane passes through the second heater; heating the composite membrane and the second solid electrolyte membrane by a second heater; and The heated composite membrane and the second solid electrolyte membrane are composited by a second shaping roller assembly to obtain a composite electrode.

[0006] In some embodiments, at least one of the first shaping roller assembly and the second shaping roller assembly is configured as an elastic rolling assembly.

[0007] In some embodiments, between the first shaping roller assembly and the second shaping roller assembly, a first substrate winding mechanism is used to receive the first substrate located on a side of the first solid electrolyte membrane away from the electrode sheet.

[0008] In some embodiments, downstream of the second sizing roller assembly, a second substrate located on a side of the second solid electrolyte membrane away from the electrode sheet is received by a second substrate winding mechanism.

[0009] In some embodiments, after the first substrate is separated from the composite membrane, the second solid electrolyte membrane is attached to the composite membrane and passes through the gap in the middle of the second shaping roller assembly.

[0010] In some embodiments, after the second substrate is separated from the composite pole piece, the composite pole piece is cooled.

[0011] In some embodiments, downstream of the second sizing roller assembly, the composite pole sheet is received by a composite pole sheet winding mechanism.

[0012] In some embodiments, the composite pole piece is cooled by a cooling roller between the second shaping roller assembly and the composite pole piece winding mechanism.

[0013] In some embodiments, the first shaping roller assembly includes a first rigid roller and a first elastic roller arranged opposite to the first rigid roller, and the first elastic roller is located on the side of the first solid electrolyte membrane away from the electrode pole piece; the second shaping roller assembly includes a second rigid roller and a second elastic roller arranged opposite to the second rigid roller, and the second elastic roller is located on the side of the second solid electrolyte membrane away from the electrode pole piece.

[0014] In some embodiments, the elastic rolling assembly includes a rigid roller and an elastic roller having a lower hardness than the rigid roller, and the rigid roller and the elastic roller are symmetrically distributed on both sides of the electrode sheet.

[0015] In some embodiments, the elastic roller includes a rigid roller and an elastic member, wherein the elastic member is coated on the outside of the rigid roller.

[0016] A second aspect of the present application provides a composite pole piece, which is prepared by using the aforementioned composite pole piece preparation method.

[0017] 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.

[0018] In the preparation method of the above-mentioned composite pole piece, the heating process before rolling composite makes the composite effect between the solid electrolyte membrane and the electrode pole piece better; during the rolling process of the first shaping roller assembly and the second shaping roller assembly, the buffer provided by the elastic member in the elastic roller enables the solid electrolyte membrane to better cover the positive electrode pole piece; on the other hand, during the rolling process, the electrode pole piece is thick in the middle, resulting in the force in the middle area being greater than the edge area. After rolling, the lateral thickness of the electrode pole piece tends to be consistent, avoiding the adverse effect of the phenomenon that the electrode pole piece is thick in the middle and thin at both ends on the rolling composite process; due to the combined effect of the heating process and the elastic member in the elastic roller, the electrode pole piece can be protected from being crushed, and the active material layer in the electrode pole piece can also be better combined 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart of a method for preparing a composite electrode provided in an embodiment of the present application.

[0020] Figure 2 This is a schematic diagram of the structure of the composite electrode preparation device provided in Example 1 of the present application.

[0021] Figure 3 A schematic diagram of the structure of the composite electrode preparation device provided in Example 2 of the present application.

[0022] Description of Reference Numerals 11. Electrode pole piece unwinding mechanism; 12. Composite pole piece winding mechanism; 21. First solid electrolyte membrane unwinding mechanism; 22. First substrate winding mechanism; 23. Second solid electrolyte membrane unwinding mechanism; 24. Second substrate winding mechanism; 31. first elastic roller; 32. first rigid roller; 33. second rigid roller; 34. second elastic roller; 41. a first heater; 42. a second heater; 51. The first guide roller; 52. The second guide roller; 53. The third guide roller; 54. The fourth guide roller; 55. The fifth guide roller; 56. The sixth guide roller; 57. The seventh guide roller; 58. The eighth guide roller; 59. The ninth guide roller; 60. The tenth guide roller; 61. The eleventh guide roller; 62. The twelfth guide roller; 63. The thirteenth guide roller. Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] See also Figure 2-3 As shown, a composite electrode sheet preparation device for preparing the composite electrode sheet of the present application includes an electrode sheet unwinding mechanism, a first solid electrolyte membrane unwinding mechanism, a second solid electrolyte membrane unwinding mechanism, a first heater, a second heater, a first shaping roller assembly, a second shaping roller assembly and a composite electrode sheet winding mechanism. The first shaping roller assembly is located upstream of the second shaping roller assembly, and at least one of the first shaping roller assembly and the second shaping roller assembly is configured as an elastic rolling assembly; the elastic rolling assembly includes a rigid roller and an elastic roller with a lower hardness than the rigid roller, and the connecting line between the rigid roller and the elastic roller axis is perpendicular to the conveying direction of the electrode sheet.

[0031] In some embodiments, the first shaping roller assembly and the second shaping roller assembly each include two rollers symmetrically arranged on both sides of the electrode sheet, and a connecting line between the axes of the two rollers is perpendicular to a conveying direction of the electrode sheet.

[0032] Optionally, the first shaping roller assembly includes a rigid roller and an elastic roller; and the second shaping roller assembly includes two rigid rollers.

[0033] Alternatively, the first shaping roller assembly and the second shaping roller assembly each include a rigid roller and an elastic roller.

[0034] Alternatively, the first shaping roller assembly includes two rigid rollers; and the second shaping roller assembly includes a rigid roller and an elastic roller.

[0035] Preferably, the first shaping roller assembly and the second shaping roller assembly each include a rigid roller and an elastic roller. Figure 2 As shown, the first shaping roller assembly includes a first rigid roller 32 and a first elastic roller 31 arranged opposite to the first rigid roller 32, and the first elastic roller 31 is located on the side of the first solid electrolyte membrane away from the electrode pole piece; the second shaping roller assembly includes a second rigid roller 33 and a second elastic roller 34 arranged opposite to the second rigid roller 33, and the second elastic roller 34 is located on the side of the second solid electrolyte membrane away from the electrode pole piece.

[0036] The first solid electrolyte membrane and electrode sheet are preheated before entering the first shaping roller assembly; the preheated first solid electrolyte membrane and electrode sheet will soften compared to before preheating, so that the ductility of the first solid electrolyte membrane and electrode sheet is improved; so that when the first shaping roller assembly rolls the first solid electrolyte membrane and electrode sheet, the first solid electrolyte membrane and electrode sheet bite more tightly, improving the bonding strength between the two and further improving their composite effect. Similarly, the second solid electrolyte membrane and composite membrane are heated before entering the second shaping roller assembly, which can also improve the composite effect between the second solid electrolyte membrane and the composite membrane, thereby obtaining a composite electrode sheet with better composite effect.

[0037] Preferably, when a substrate is provided on the solid electrolyte membrane, the substrate covers a side of the solid electrolyte membrane away from the electrode plate.

[0038] As an implementation mode, after the electrode sheet and the first solid electrolyte membrane are rolled by a first shaping roller assembly to obtain a composite membrane sheet, the first substrate is separated.

[0039] Preferably, the first substrate is separated from the composite membrane by arranging a first substrate winding mechanism between the first shaping roller assembly and the second shaping roller assembly, so as to improve the heating effect of the second solid electrolyte membrane in the subsequent second heater, and also improve the composite effect between the composite membrane and the second solid electrolyte membrane; the first substrate winding mechanism and the first solid electrolyte membrane unwinding mechanism are located on the same side of the electrode sheet unwinding mechanism, and are used to receive the substrate covering the side of the first solid electrolyte away from the electrode sheet.

[0040] After the first solid electrolyte membrane is combined with the electrode plate, the substrate is preferably separated from the composite membrane by a substrate separation device, so that the composite membrane avoids the influence of the substrate when entering the second heater.

[0041] When the second substrate needs to be separated after the composite membrane and the second solid electrolyte membrane are rolled by the second shaping roller assembly to obtain a composite electrode sheet, the second substrate is separated from the composite electrode sheet by setting a second substrate winding mechanism downstream of the second shaping roller assembly; the second substrate winding mechanism and the first substrate winding mechanism are located on both sides of the electrode electrode sheet unwinding mechanism, and are used to receive the substrate covering the side of the second solid electrolyte away from the electrode electrode sheet. During the separation process, the first substrate winding mechanism and the second substrate winding mechanism will respectively provide pulling force to the first substrate and the second substrate, so that the first and second substrates are separated from the composite membrane or the composite electrode sheet, and the action of winding the substrate is completed when necessary.

[0042] Optionally, the first substrate winding mechanism is located between the first shaping roller assembly and the second shaping roller assembly.

[0043] Alternatively, the first substrate winding mechanism and the second substrate winding mechanism are both located downstream of the second shaping roller assembly, and are symmetrically arranged on both sides of the composite pole piece winding mechanism.

[0044] In some embodiments, a heating device may be disposed inside the rigid rollers in the first shaping roller assembly and the second shaping roller assembly to improve the laminating effect. The elastic roller may optionally be provided with a heating device inside.

[0045] The electrode sheet unwinding mechanism is located upstream of the first shaping roller assembly and the first heater, and is used to unwind the electrode sheet, then transport the electrode sheet so that the electrode sheet reaches the first heater for heating, and then continue to transport the heated electrode sheet to the gap in the middle of the first shaping roller assembly.

[0046] The first solid electrolyte membrane unwinding mechanism is located upstream of the first shaping roller assembly and the first heater, and more specifically, between the electrode sheet unwinding mechanism and the first heater. The first solid electrolyte membrane unwinding mechanism is used to unwind the first solid electrolyte membrane, then transport the first solid electrolyte membrane so that the first solid electrolyte membrane reaches the first heater for heating, and then transport the heated first solid electrolyte membrane to the gap in the middle of the first shaping roller assembly.

[0047] The second solid electrolyte membrane unwinding mechanism is located downstream of the first shaping roller assembly, and more specifically, between the first shaping roller assembly and the second heater. The second solid electrolyte membrane unwinding mechanism is used to unwind the second solid electrolyte membrane, and then transport the second solid electrolyte membrane so that the second solid electrolyte membrane reaches the second heater for heating, and then continue to transport the heated second solid electrolyte membrane to the gap in the middle of the second shaping roller assembly.

[0048] The first heater is located between the electrode sheet unwinding mechanism and the first shaping roller assembly, more specifically between the first solid electrolyte membrane unwinding mechanism and the first shaping roller assembly, and is used to heat the electrode sheet and / or the first solid electrolyte membrane.

[0049] The internal channels of the first heater and the second heater are parallel to the running direction of the electrode plates, that is, during the whole process from entering the first heater / second heater to leaving the first heater / second heater, the movement direction of the electrode plates and / or the first solid electrolyte membrane and / or the second solid electrolyte membrane remains consistent. This heating method reduces the relative displacement of the electrode plates, the first solid electrolyte membrane and the second solid electrolyte membrane during movement, and to a certain extent ensures the composite effect of the electrode plates, the first solid electrolyte membrane and the second solid electrolyte membrane.

[0050] It is understandable that the present application preheats the electrode plate and the solid electrolyte membrane by setting the first heater and the second heater, and the present application does not specifically limit the type and structure of the first heater and the second heater. As an illustrative example, the path of the first heater heating the electrode plate and the first solid electrolyte membrane is the same as the running direction of the electrode plate, so as to reduce unnecessary relative displacement of the electrode plate and the first solid electrolyte membrane during the heating process.

[0051] In some embodiments, the first heater and the second heater adopt blast heating, radiation heating and contact heating. One or more rollers may be arranged inside the first heater and the second heater to provide support for the electrode sheet and / or the first solid electrolyte membrane, so that the electrode sheet and / or the first solid electrolyte membrane can pass through the first heater and the second heater more smoothly and the heating of the two is more uniform.

[0052] Preferably, heat-insulating materials are provided in the channels of the first heater and the second heater to avoid heat loss and further improve the heating effect.

[0053] In some embodiments, the temperatures of the first heater and the second heater can be adjusted as needed. Preferably, the temperatures of the first heater and the second heater are higher than the softening temperatures of the pole piece and the solid electrolyte membrane.

[0054] It can be understood that the softening temperature of the above-mentioned electrode plate and solid electrolyte membrane refers to the temperature above which the surface hardness of the electrode plate or solid electrolyte changes, and the electrode and solid electrolyte membrane form a complete composite structure under the action of rolling pressure.

[0055] The second heater is located between the first and second shaping roller assemblies and is used to heat the second solid electrolyte membrane.

[0056] In some embodiments, one or more rollers may be disposed inside the first heater and the second heater to provide support for the composite membrane and / or the second solid electrolyte membrane.

[0057] It can be understood that the longitudinal lengths of the first heater and the second heater along the running direction of the electrode plate are adjustable, so as to meet different heating time requirements.

[0058] In some embodiments, the first heater and the second heater further include a sensor for detecting an internal temperature.

[0059] The composite electrode sheet winding mechanism is located downstream of the second shaping roller assembly, and is used to provide a pulling force along the moving direction of the electrode sheet to the electrode sheet, and receive the composite electrode sheet obtained after being rolled by the second shaping roller assembly to complete the winding action.

[0060] In some embodiments, the composite pole piece preparation device further includes a first substrate winding mechanism and a second substrate winding mechanism.

[0061] In some embodiments, the composite pole piece preparation device further includes a cooling roller, located downstream of the second shaping roller assembly, for cooling the composite pole piece. The present application provides a cooling roller to reduce 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 also provides a shaping effect for the composite pole piece.

[0062] The number of cooling rollers may be one or more, preferably two.

[0063] Preferably, the cooling roller of the present application adopts a contact cooling roller, which has a better cooling effect.

[0064] In some embodiments, the cooling roller further comprises a sensor for detecting the surface temperature of the composite pole piece.

[0065] In some embodiments, the composite pole piece preparation device further includes a guide roller.

[0066] Optionally, the guide roller is located between the first solid electrolyte membrane unwinding mechanism and the first shaping roller assembly, and is used to provide a guide for the first solid electrolyte membrane and / or the electrode sheet. Figure 2 As shown, the first solid electrolyte membrane starts from the first solid electrolyte membrane unwinding mechanism 21, passes through the first guide roller 51, and then meets and fits with the electrode sheet starting from the electrode sheet unwinding mechanism 11 at the second guide roller 52. The electrode sheet and the first solid electrolyte membrane pass through the first heater 41 and then reach the first shaping roller assembly for the first compounding.

[0067] By adjusting the relative position between the guide roller and the first heater, on the one hand, it can be ensured that the electrode plate and the first solid electrolyte membrane are first bonded and then heated together, and further ensure that the temperature of the electrode plate and the first solid electrolyte membrane is consistent during rolling and compounding, avoiding the phenomenon of high defective rate caused by cracking due to temperature difference during rolling. On the other hand, the running direction of the electrode plate and / or the first solid electrolyte membrane can be always parallel to the first heater. In this case, the movement process of the electrode plate and / or the first solid electrolyte membrane is smoother and the possibility of relative displacement is also reduced.

[0068] Optionally, the guide roller is located between the first shaping roller assembly and the first substrate winding mechanism 22, and is used to provide a guide for the first substrate of the first solid electrolyte membrane separated from the composite electrode sheet. Figure 2 As shown, after the electrode sheet and the first solid electrolyte membrane are combined at the first shaping roller assembly to form a composite membrane sheet, the composite membrane sheet continues to move toward the second shaping roller assembly. The first substrate is subjected to the force transmitted by the first substrate winding mechanism 22 via the third guide roller 53 and the fourth guide roller 54, so that the first substrate is separated from the composite membrane sheet at the third guide roller 53, and the first substrate winding mechanism 22 completes the winding action.

[0069] Optionally, the guide roller is located between the second solid electrolyte membrane unwinding mechanism 23 and the second shaping roller assembly to provide a guide for the second solid electrolyte membrane and / or the composite membrane. Figure 2 As shown, the second solid electrolyte membrane starts from the second solid electrolyte membrane unwinding mechanism 23, passes through the sixth guide roller 56, and then meets and fits with the composite membrane sheet at the seventh guide roller 57. The composite membrane sheet and the second solid electrolyte membrane pass through the fifth guide roller 55, the sixth guide roller 56, and the seventh guide roller 57, and then arrive at the second heater 42 together with the second solid electrolyte membrane. The composite membrane sheet and the second solid electrolyte membrane pass through the second heater 42 together and arrive at the second shaping roller assembly for the second composite.

[0070] Optionally, the guide roller is located between the second shaping roller assembly and the second substrate winding mechanism 24, and is used to provide a guide for the second substrate of the second solid electrolyte membrane separated from the composite electrode sheet. Figure 2 As shown, after the composite membrane and the second solid electrolyte membrane are combined at the second shaping roller assembly to form a composite electrode, the composite electrode continues to move toward the composite electrode winding mechanism 12. The second substrate is separated from the composite electrode at the roller pair formed by the eighth guide roller 58 and the tenth guide roller 60, and the second substrate is moved toward the second substrate winding mechanism 24 by the force transmitted by the second substrate winding mechanism 24 via the ninth guide roller 59 and the winding action is completed by the second substrate winding mechanism 24.

[0071] Optionally, the guide roller is located between the second shaping roller assembly and the composite pole piece winding mechanism 12, and is used to provide a guiding effect on the composite pole piece. Figure 2 As shown, after the composite membrane and the second solid electrolyte membrane are combined at the second shaping roller assembly to form a composite electrode, the composite electrode continues to move toward the composite electrode winding mechanism 12. The composite electrode is separated from the second substrate at the roller pair formed by the eighth guide roller 58 and the tenth guide roller 60, and reaches the first cooling roller 43 after adjusting the direction through the eleventh guide roller 61 and the twelfth guide roller 62. The composite electrode rotates around the first cooling roller 43 for a certain angle and reaches the second cooling roller 44. After rotating around the second cooling roller 44 for a certain angle, it moves forward to the composite electrode winding mechanism 12 and completes the winding action of the composite electrode. If necessary, a thirteenth guide roller 63 can also be set between the second cooling roller 46 and the composite electrode winding mechanism 12 to adjust the direction of the composite electrode.

[0072] In some embodiments, the composite electrode preparation device also includes a tension control device, an unwinding correction component, an electrode anti-static component, etc., which are sequentially arranged along the unwinding route. The tension control device includes a plurality of tension control elements arranged upstream of the rolling device, which are respectively used to control the unwinding tension of the positive electrode sheet and the solid electrolyte membrane. Optionally, the tension control device includes a plurality of tension control elements arranged downstream of the rolling device, which are respectively used to control the winding tension of the composite positive electrode sheet and the substrate. The unwinding correction component can correct the unwinding and running routes of the electrode sheet and the solid electrolyte membrane, etc., so that the starting material line remains at the same level. The unwinding mechanism of the main material adopts a single-station correction, and the unwinding 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 sheet, which can reduce the friction between the electrode sheet 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.

[0073] In some embodiments, the width of the first shaping roller assembly and the second 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.

[0074] In some embodiments, the roller diameters of the first shaping roller assembly and the second shaping roller assembly are 300-500 mm, including but not limited to 300 mm, 350 mm, 400 mm, 450 mm, 500 mm, preferably 350-450 mm.

[0075] In some embodiments, the mechanical speed of the sizing roller assembly 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.

[0076] 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.

[0077] 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.

[0078] See also Figure 2-3 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 electrode sheet through the electrode electrode sheet unwinding mechanism 11 and conveying the electrode electrode sheet to the composite electrode sheet rewinding mechanism 12, and at the same time unwinding the first solid electrolyte membrane through the first solid electrolyte membrane unwinding mechanism 21; the electrode electrode sheet and the first solid electrolyte membrane first arrive at the first heater for heating, and then the electrode electrode sheet and the first solid electrolyte membrane continue to move forward to the first shaping roller assembly, and form a composite membrane sheet under the rolling action of the first shaping roller assembly; the composite membrane sheet moves to the second shaping roller assembly, and at the same time, the second solid electrolyte membrane unwinding mechanism unwinds the second solid electrolyte membrane, the composite membrane sheet and the second solid electrolyte membrane arrive at the second heater, and after heating the second solid electrolyte membrane, arrive at the second shaping roller assembly, and form a composite electrode sheet under the action of the second shaping roller assembly, and the composite electrode sheet rewinding mechanism completes the rewinding.

[0079] The present application divides the process of composite solid electrolyte membrane on both sides of the pole piece into two steps through the first shaping roller assembly and the second shaping roller assembly. Different process temperatures can be set according to the characteristics of the solid electrolyte membrane on both sides of the pole piece, thereby improving the composite effect of the pole piece and the solid electrolyte membrane.

[0080] In some embodiments, at least one of the first shaping roller assembly and the second shaping roller assembly is configured as an elastic rolling assembly; the elastic rolling assembly includes a rigid roller and an elastic roller having a lower hardness than the rigid roller, and a connecting line between the axes of the rigid roller and the elastic roller is perpendicular to the conveying direction of the electrode sheet.

[0081] 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 first solid electrolyte membrane enter the gap of the first shaping roller assembly, a composite membrane sheet is obtained under the pressure of the first shaping roller assembly; after the composite membrane sheet and the second solid electrolyte membrane advance into the gap of the second shaping roller assembly, a composite electrode sheet is obtained under the rolling action of the second shaping roller assembly, and finally the composite electrode sheet can be rolled up by the electrode sheet rolling mechanism 12.

[0082] In some embodiments, the solid electrolyte membrane is covered with a layer of substrate for providing support for the solid electrolyte membrane. When the first solid electrolyte membrane unwinding mechanism 21 conveys the first solid electrolyte membrane, the first substrate is located on the side of the first solid electrolyte membrane away from the electrode sheet, and when the second solid electrolyte membrane unwinding mechanism 23 conveys the second solid electrolyte membrane, the second substrate is located on the side of the second solid electrolyte membrane away from the electrode sheet. After the first solid electrolyte membrane and the electrode sheet are fully composited, the first substrate is separated from the composite membrane sheet, and after the second solid electrolyte membrane and the composite membrane sheet are fully composited, the second substrate is separated from the composite electrode sheet. Specifically, the first substrate can be received by the first substrate winding mechanism 22 located on the same side of the electrode sheet as the first solid electrolyte membrane unwinding mechanism 21, and the first substrate winding mechanism 22 is between the first shaping roller assembly and the second shaping roller assembly; the second substrate is received by the second substrate winding mechanism 24 located on the same side of the electrode sheet as the second solid electrolyte membrane unwinding mechanism 23, and the second substrate winding mechanism 24 is between the second shaping roller assembly and the composite electrode sheet winding mechanism 12.

[0083] In some embodiments, after the second shaping roller assembly completes rolling and before the composite electrode sheet winding mechanism winds up, a thickness measuring mechanism is used to inspect the composite electrode sheet, and the composite electrode sheet is wound up by the winding mechanism after passing the inspection.

[0084] See also Figure 1 , Figure 1 The flowchart of the method for preparing a composite pole piece by using the composite pole piece preparation device of the present invention is shown, comprising: S10: heating the electrode plate and the first solid electrolyte membrane by a first heater; S20: Compounding the heated electrode sheet and the first solid electrolyte membrane by a first shaping roller assembly to obtain a composite membrane; S30: heating the second solid electrolyte membrane by a second heater; S40: Compounding the heated second solid electrolyte membrane and the composite membrane sheet through a second shaping roller assembly to obtain a composite electrode sheet.

[0085] At least one of the first shaping roller assembly and the second shaping roller assembly is configured as an elastic rolling assembly. The elastic rolling assembly includes a rigid roller and an elastic roller having a lower hardness than the rigid roller, and the elastic roller faces the first solid electrolyte membrane or the second solid electrolyte membrane for compounding. During the rolling process, the elastic roller adjusts the stress conditions of the electrode sheet and the solid electrolyte membrane, so that the composite sheet after rolling and the solid electrolyte membrane can better cover the electrode sheet; and the lateral thickness of the electrode sheet after rolling tends to be consistent.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] In some embodiments, the electrode plates and the solid electrolyte membrane are both prepared by a dry process.

[0090] In some embodiments, at least one of the electrode sheet and the solid electrolyte membrane is prepared by a dry process.

[0091] In some embodiments, the electrode plates and the solid electrolyte membrane are both prepared by a wet process.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 contains 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.

[0098] 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 the conductive material; and greater than or equal to about 0 wt% to less than or equal to about 20 wt% of the binder.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] In some embodiments, both the front and back sides of the current collector layer include active material layers.

[0103] In some embodiments, the current collector layer may be a metal foil or a composite current collector.

[0104] For example, the metal foil may be aluminum foil.

[0105] 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.

[0106] 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.

[0107] In some embodiments, the electrode plate is a negative electrode plate.

[0108] 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).

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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)).

[0113] Alternatively, the negative electrode active material in the negative electrode sheet may be doped with one or more conductive materials providing 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.

[0114] 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.

[0115] Dry preparation As mentioned in the background technology, due to the high strength and poor deformation resistance of the traditional shaping roller assembly, the electrode plate is chamfered for the smooth rolling process, forming a structure with thick middle and thin ends. 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, it will be difficult for the electrode plate 1 and the solid electrolyte membrane 2 to be tightly compounded because the middle area and the edge area of ​​the electrode plate 1 are subjected to different rolling forces of the steel roller, which is an invalid compound, resulting in 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.

[0116] The preparation method of the present application utilizes the buffer provided by the elastic roller in the elastic rolling assembly during the rolling of the shaping roller assembly, 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 the edge area, and the lateral thickness of the electrode sheet tends to be consistent after rolling. This avoids the adverse effects of the rolling composite 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 better combine the active material layer in the electrode sheet 1 with the solid electrolyte membrane 2. In addition, during the rolling process of the shaping roller assembly, 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.

[0117] In some embodiments, a solid electrolyte membrane includes a solid electrolyte and a binder.

[0118] 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.

[0119] 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.

[0120] 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 LLZO, 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 6.75La3Zr 1.75 Nb 0.25 O 12 One or more of. One or more LISICON-type oxides include, but are not limited to, Li 14 Zn(GeO4)4, Li 3+x (P 1−x Si x )O4 (where 0 < x < 1), Li 3+x Ge x V 1-x O4 (where 0 < x < 1). One or more NASICON-type oxides can be defined by LiMMʹ(PO4)3, where M and Mʹ 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).

[0121] Sulfide solid electrolytes include but are not limited to Li2S-P2S5, Li2S-P2S5-MS x (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).

[0122] Halide solid electrolytes include but are not limited to Li2CdC l4 、Li2MgC l4 、Li2Cd I4, Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x One or more of which 0 < x < 1.

[0123] The boride solid electrolyte includes but is not limited to one or more of Li2B4O7, Li2O-(B2O3)-(P2O5).

[0124] The nitride solid electrolyte includes but is not limited to one or more of Li3N, Li7PN4, LiSi2N3, LiPON.

[0125] 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.

[0126] 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.

[0127] In some embodiments, the solid electrolyte further includes a partial polymer solid electrolyte, a composite solid electrolyte composed of the polymer solid electrolyte and the inorganic solid electrolyte. In the embodiments of the present application, there is no special requirement for the mass ratio of the inorganic solid electrolyte and the polymer solid electrolyte in the composite solid electrolyte, and the user can design it according to actual needs. Among them, the polymer solid electrolyte can be at least one of polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and polyethylene oxide (PEO).

[0128] In some embodiments, the polymer solid electrolyte contains a lithium salt.

[0129] 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).

[0130] 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.

[0131] In some embodiments, the thickness of the solid electrolyte membrane is 1-40 μm. The solid electrolyte membrane can effectively improve the safety performance of the battery, but if the solid electrolyte is too thick, it will affect the energy density of the battery; it is understood that when the solid electrolyte membrane includes a substrate, the thickness of the solid electrolyte membrane does not include the thickness of the substrate.

[0132] Preferably, the thickness of the solid electrolyte membrane is 1-30 μm, preferably 3-20 μm, and more preferably 3-15 μm. The maximum surface density of the solid electrolyte membrane is 4 mg / cm2, and the width can be 0.6 m.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] The present application does not specifically limit the type of substrate. Without violating the inventive concept of the present application, any known material with a certain supporting function, which is 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-silicon release film. The present application also provides a composite pole piece, which is prepared according to the preparation method of the composite pole piece provided above.

[0137] As an embodiment, the first solid electrolyte membrane and the second solid electrolyte membrane have different compositions.

[0138] Further, the temperature of the first heater is different from the temperature of the second heater and / or the pressure of the first shaping roller is different from the pressure of the second shaping roller.

[0139] It can be understood that the composition of the first solid electrolyte membrane and the second solid electrolyte membrane is different, which can be understood as the material system or structural composition of the solid electrolyte membrane is different. This difference makes the composite process of the first solid electrolyte membrane or the second solid electrolyte membrane different. The present application uses two composite processes before and after, and different composite processes can be set according to the different composite performances of the first solid electrolyte membrane and the second solid electrolyte membrane with the positive electrode sheet.

[0140] In some embodiments, the elastic roller is configured to surround and cover the elastic member on the outside of the rigid roller. When the elastic roller rotates, the elastic member rotates with the elastic roller; and when the shaping roller assembly rolls the first solid electrolyte membrane, the electrode sheet, and the second solid electrolyte membrane, the elastic member provides a buffering effect, so that the first solid electrolyte membrane and the second solid electrolyte membrane can better cover 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.

[0141] It is understandable that during the production of electrode sheets, in order to ensure the smooth progress of the subsequent rolling process, the edges of the electrode sheets are usually thinned, and the existence of the thinned area of ​​the electrode sheets affects the fit between the solid electrolyte membrane and the electrode sheets; if the electrode sheets and the solid electrolyte membrane cannot form an effective composite in the thinned area, the formed composite sheets are prone to form cracks in the edge area.

[0142] 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 assembly, 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] In some embodiments of the present invention, the flexible material is a polymer. The present application does not impose any particular restrictions on the material of the polymer. For example, it can be a plastic such as polytetrafluoroethylene, polyethylene terephthalate, polypropylene, polyacrylonitrile, or a rubber such as Hypalon rubber, silicone rubber, fluororubber, or an elastic material such as silicone that can be deformed to a certain extent. A hard rubber with high heat resistance is preferred.

[0149] 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.

[0150] In some embodiments, the elastic roller can also be configured to partially surround and cover the elastic member on the outer side of the rigid roller, so that when the shaping roller assembly is rolled and compounded, the elastic member is located between the first or second solid electrolyte membrane and the shaping roller assembly. Exemplarily, the first elastic roller 31 can be replaced by a rigid roller with a protective film made of a flexible material. The specific protective film can be unwound through the gap in the middle of the first shaping roller assembly by a protective film unwinding mechanism located between the first heater 41 and the first elastic roller 31. In the first shaping roller assembly, the rigid roller, the protective film, the first solid electrolyte membrane, the electrode plate and the rigid roller are distributed from top to bottom. During rolling, the protective film replaces the elastic member in the first elastic roller to play a buffering role.

[0151] The present application further provides a lithium-ion battery, which includes the composite pole piece provided above.

[0152] In some embodiments, the electrode plates and the solid electrolyte membrane may also be purchased.

[0153] 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. Example

[0154] 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.

[0155] 2. Preparation of solid electrolyte membrane LLZO is selected as a solid electrolyte, polytetrafluoroethylene is selected as a binder, and LiPF6 is selected as a lithium salt. The above substances are mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. The mixture is then subjected to a fiberization treatment by air flow milling to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture is rolled to obtain a solid electrolyte membrane.

[0156] 3. Preparation of composite positive electrode sheet Through Figure 2 The composite electrode sheet preparation device provided with a protective film is shown, which composites the positive electrode sheet with the first and second solid electrolyte membranes. The elastic member is Hypalon rubber, and the first flat heater is a radiation heater.

[0157] The first solid electrolyte membrane starts from the first solid electrolyte membrane unwinding mechanism 21, passes through the first guide roller 51, and then meets and fits with the electrode sheet starting from the electrode sheet unwinding mechanism 11 at the second guide roller 52. The electrode sheet and the first solid electrolyte membrane pass through the first heater 41 and then reach the first shaping roller assembly for the first compounding, wherein the electrode sheet is farther away from the first elastic roller 31 than the first solid electrolyte membrane. After the compounding is completed, the first substrate is subjected to the force transmitted by the first substrate winding mechanism 22 via the third guide roller 53 and the fourth guide roller 54, so that the first substrate is separated from the composite membrane sheet between the third guide roller 53 and the fifth guide roller 55, and the first substrate winding mechanism 22 completes the winding action.

[0158] The second solid electrolyte membrane starts from the second solid electrolyte membrane unwinding mechanism 23, passes through the sixth guide roller 56, and meets and fits with the composite membrane sheet behind the seventh guide roller 57. The composite membrane sheet starts from the first shaping roller assembly, separates from the first substrate, and then fits with the second solid electrolyte membrane at the seventh guide roller 57. The electrode sheet and the second solid electrolyte membrane pass through the second heater 42 together and arrive at the second shaping roller assembly for a second composite, wherein the composite membrane sheet is farther away from the second elastic roller 34 than the second solid electrolyte membrane. After the composite is completed, the second substrate is subjected to the force transmitted by the second substrate winding mechanism 24 via the ninth guide roller 59 and the eighth guide roller 58, and is separated from the composite electrode sheet at the eighth guide roller 58, and is finally rolled up by the second substrate winding mechanism 24; wherein the eighth guide roller 58 is as Figure 2 As shown, next to the route of the composite pole piece, the second substrate is in an S-shaped direction between the eighth guide roller 58 and the ninth guide roller 59. The composite pole piece is adjusted in direction by the eleventh guide roller 61 and the twelfth guide roller 62, cooled by the first cooling roller 43 and the second cooling roller 44, and finally rolled up by the composite pole piece rolling mechanism 12.

[0159] The temperature of the first setting roller and the first heater is 160°C, and the temperature of the second setting roller and the second heater is 180°C; The prepared composite pole piece has no cracks on its surface, and the overall thickness of the composite pole piece is 160 μm. Example

[0160] 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.

[0161] 2. Preparation of solid electrolyte membrane A preselected solid electrolyte material is selected, polytetrafluoroethylene is used as a binder, the above substances are mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. The mixture is then subjected to a fiberization treatment by mechanical stirring to obtain a fiberized solid electrolyte mixture, and the fiberized solid electrolyte mixture is rolled to obtain a solid electrolyte membrane.

[0162] Among them, the raw materials of the first solid electrolyte membrane are LLZO and PTFE particles, the stirring speed of the fiberization process is 12000rpm, and the preset thickness is 15μm; the raw materials of the second solid electrolyte membrane are LLZO and PTFE fiber membrane, the stirring speed of the fiberization process is 8000rpm, and the preset thickness is 17μm.

[0163] 3. Preparation of composite positive electrode sheet Through Figure 3 The composite electrode sheet preparation device provided with a protective film is shown, and the positive electrode sheet is composited with the first and second solid electrolyte membranes. The elastic member is Hypalon rubber. The difference from Example 1 is that the separation angle is not controlled when the first substrate is separated from the composite membrane sheet, and when the second substrate is separated from the composite electrode sheet.

[0164] The first solid electrolyte membrane starts from the first solid electrolyte membrane unwinding mechanism 21, passes through the first guide roller 51, and then meets and fits with the electrode sheet starting from the electrode sheet unwinding mechanism 11 at the second guide roller 52. The electrode sheet and the first solid electrolyte membrane pass through the first heater 41 and then reach the first shaping roller assembly for the first compounding, wherein the electrode sheet is farther away from the first elastic roller 31 than the first solid electrolyte membrane. After the compounding is completed, the first substrate is subjected to the force transmitted by the first substrate winding mechanism 22 via the third guide roller 53 and the fourth guide roller 54, so that the first substrate is separated from the composite membrane sheet between the third guide roller 53 and the fifth guide roller 55, and the first substrate winding mechanism 22 completes the winding action.

[0165] The second solid electrolyte membrane starts from the second solid electrolyte membrane unwinding mechanism 23, passes through the sixth guide roller 56, and meets and fits with the composite membrane sheet behind the seventh guide roller 57. The composite membrane sheet starts from the first shaping roller assembly, separates from the first substrate, and then fits with the second solid electrolyte membrane at the seventh guide roller 57. The electrode sheet and the second solid electrolyte membrane pass through the second heater 42 and then reach the second shaping roller assembly for the second composite, wherein the composite membrane sheet is farther away from the second elastic roller 34 than the second solid electrolyte membrane. The temperature of the first shaping roller and the first heater is 160°C, and the temperature of the second shaping roller and the second heater is 180°C.

[0166] After the composite is completed, the second substrate moves toward the composite electrode sheet reeling mechanism 12 together with the composite electrode sheet. At the same time, the second substrate is subjected to the force transmitted by the second substrate reeling mechanism 24 via the ninth guide roller 59 and the eighth guide roller 58, and is separated from the composite electrode sheet at the eighth guide roller 58. After the second substrate passes around the same side of the eighth guide roller 58 and the ninth guide roller 59, it is finally reeled by the second substrate reeling mechanism 24; wherein the eighth guide roller 58 is close to the path of the composite electrode sheet. The composite electrode sheet is cooled by the first cooling roller 45 and the second cooling roller and then reeled by the composite electrode sheet reeling mechanism 12.

[0167] The prepared composite pole piece has no cracks on its surface and the overall thickness of the pole piece is 165 μm.

[0168] 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.

[0169] 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 preparation method comprises: The electrode sheet is conveyed by an electrode sheet unwinding mechanism so that the electrode sheet passes through a first heater; The first solid electrolyte membrane is conveyed by a first solid electrolyte membrane unwinding mechanism located on one side of the electrode sheet unwinding mechanism; Compounding the heated electrode sheet and the first solid electrolyte membrane by a first shaping roller assembly to obtain a composite membrane sheet; The second solid electrolyte membrane is conveyed by a second solid electrolyte membrane unwinding mechanism located on the other side of the electrode sheet unwinding mechanism; as well as Compounding the composite membrane and the second solid electrolyte membrane by a second shaping roller assembly to obtain a composite electrode; The first shaping roller assembly includes a first rigid roller and a first elastic roller arranged opposite to the first rigid roller, and the first elastic roller is located on a side of the first solid electrolyte membrane away from the electrode sheet; The second shaping roller assembly includes a second rigid roller and a second elastic roller arranged opposite to the second rigid roller, and the second elastic roller is located on a side of the second solid electrolyte membrane away from the electrode plate.

2. The preparation method according to claim 1, characterized in that: The preparation method further includes: receiving a first substrate located on a side of the first solid electrolyte membrane away from the electrode plate by a first substrate winding mechanism between the first shaping roller assembly and the second shaping roller assembly.

3. The preparation method according to claim 1, characterized in that: The preparation method further includes: receiving a second substrate located on a side of the second solid electrolyte membrane away from the electrode plate by a second substrate winding mechanism downstream of the second shaping roller assembly.

4. The preparation method according to claim 2, characterized in that: After the first substrate is separated from the composite membrane, the second solid electrolyte membrane is attached to the composite membrane and passes through the gap in the middle of the second shaping roller assembly.

5. The preparation method according to claim 3, characterized in that: After the second substrate is separated from the composite pole piece, the composite pole piece is cooled.

6. The preparation method according to claim 1, characterized in that: The preparation method further includes: receiving the composite pole piece by a composite pole piece winding mechanism downstream of the second shaping roller assembly.

7. The preparation method according to claim 6, characterized in that: The preparation method further includes: cooling the composite pole piece by a cooling roller between the second shaping roller assembly and the composite pole piece winding mechanism.

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

9. A lithium ion battery, characterized in that: The composite electrode is prepared by the method according to any one of claims 1 to 8.

Images