Method for preparing composite electrode sheet, composite electrode sheet, and solid-state battery

Abstract

The application relates to a preparation method of a composite electrode sheet. First, a solid electrolyte film is heated through a shaping roller assembly; then the electrode sheet and the aforementioned heated solid electrolyte film are heated and roll-compressed through the shaping roller assembly to obtain a composite electrode sheet; wherein an elastic piece is arranged between the shaping roller assembly and the solid electrolyte film roll-compressed on the electrode sheet; the electrode sheet comprises a positive electrode sheet and a negative electrode sheet. The method improves the composite effect between the solid electrolyte film and the electrode sheet through a heating process, and the consistency of the transverse thickness of the composite electrode sheet is improved through the elastic piece in the preparation process.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for preparing a composite electrode, the composite electrode prepared by the method, and a solid-state battery containing the composite electrode. Background Technology

[0002] Studies have shown that coating the surface of electrode sheets with a solid electrolyte film can help improve battery safety. However, wet coating methods present a series of problems, such as the tendency for binders to segregate during the coating drying process, which can pose safety hazards. Furthermore, wet processes require large amounts of solvents, polluting the surrounding environment. Dry electrode technology has been extensively reported, but there are few reports on how to use dry technology to laminate solid electrolyte films onto electrode surfaces. Due to the differences in material systems between the electrode and the solid electrolyte film, dry composite processes often result in poor mechanical properties of the composite film and insufficient interlayer bonding. Summary of the Invention

[0003] Therefore, it is necessary to provide a method for preparing composite electrodes, which overcomes the problem of poor composite effect of solid electrolyte membrane caused by the thinning of the electrode edge, and improves the consistency of the lateral thickness of the composite electrode formed by the electrode and the solid electrolyte membrane.

[0004] A method for preparing a composite electrode includes: preheating a solid electrolyte membrane using a shaping roller assembly, wherein the shaping roller assembly is equipped with a heating mechanism for preheating the solid electrolyte membrane; and

[0005] The electrode sheet and the preheated solid electrolyte membrane are heated and rolled together by a shaping roller assembly to obtain a composite electrode sheet;

[0006] The electrode plates include positive electrode plates and negative electrode plates.

[0007] In some embodiments, the shaping roller assembly includes a first shaping roller and a second shaping roller; at least one of the first shaping roller and the second shaping roller is provided with a heating mechanism, and the solid electrolyte membrane located on both sides of the electrode sheet is pressed onto the electrode sheet by the first shaping roller and the second shaping roller to obtain a composite electrode sheet.

[0008] In some embodiments, both the first shaping roller and the second shaping roller are provided with a heating mechanism.

[0009] In some embodiments, an elastic element is provided between the shaping roller assembly and the solid electrolyte membrane pressed onto the electrode sheet;

[0010] Optionally, the elastic element is a protective film that is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

[0011] In some embodiments, the protective film is a polymer film or a nonwoven fabric.

[0012] In some embodiments, the elastic element is an adhesive layer that surrounds and covers the outside of the shaping roller assembly.

[0013] In some implementations, the adhesive layer is made of plastic, rubber, or silicone.

[0014] In some embodiments, the preparation method of this application further includes: separating the substrate covering the solid electrolyte membrane from the composite electrode.

[0015] The method for preparing the composite electrode provided in this application includes the following steps:

[0016] The electrode sheet is conveyed by the electrode sheet unwinding mechanism, so that the electrode sheet passes through the gap in the middle of the shaping roller assembly;

[0017] The solid electrolyte membrane is conveyed by a solid electrolyte membrane unwinding mechanism located on the side of the electrode unwinding mechanism, so that the solid electrolyte membrane reaches the shaping roller assembly for preheating and passes through the gap between the shaping roller assembly and the electrode sheet; and

[0018] Composite electrode sheets are obtained by heating and rolling the preheated solid electrolyte membrane with a shaping roller assembly.

[0019] During the rolling process, the temperature of the solid electrolyte membrane is higher than that of the electrode sheet.

[0020] Electrode plates include positive electrode plates and negative electrode plates.

[0021] In some embodiments, the preparation method further includes: receiving a composite electrode downstream of the shaping roller assembly via a composite electrode winding mechanism; receiving a substrate via a substrate winding mechanism between the shaping roller assembly and the composite electrode winding mechanism; the substrate winding mechanism and the solid electrolyte membrane unwinding mechanism being located on the same side of the electrode unwinding mechanism.

[0022] In some embodiments, the elastic element is a protective film, and the preparation method further includes: conveying the protective film through a protective film unwinding mechanism so that the protective film passes through the gap between the solid electrolyte membrane and the shaping roller assembly; and receiving the elastic element through a protective film winding mechanism between the shaping roller assembly and the substrate winding mechanism.

[0023] The second aspect of this application provides a composite electrode, which is obtained by the method for preparing the composite electrode described in the first aspect.

[0024] A third aspect of this application provides a solid-state battery comprising a composite electrode prepared by the method for preparing the composite electrode described in the first aspect.

[0025] The aforementioned method for preparing composite electrodes utilizes elastic elements to buffer the rolling process during the composite process. This avoids the problem of low composite efficiency caused by the poor deformation resistance of rigid rollers, and also avoids the adverse effects of the electrode sheet being thicker in the middle and thinner at both ends on the rolling composite process. When preparing composite electrodes using the method described in this application, both the solid electrolyte membrane and the electrode sheet are heated, improving their ductility. Furthermore, the heating time of the solid electrolyte membrane by the shaping roller assembly is longer than that of the electrode sheet, further enhancing the ductility of the solid electrolyte membrane. Additionally, during rolling, the electrode sheet's structure exhibits a greater thickness in the middle region than at the edges, resulting in greater stress in the middle region compared to the edges. These combined factors allow the rolled solid electrolyte membrane to better cover the surface of the electrode sheet, and improve the bonding between the active material layer in the electrode sheet and the solid electrolyte membrane, effectively enhancing the uniformity of the lateral thickness of the composite electrode sheet. Furthermore, the composite electrode prepared using the method described in this application, when applied to a battery, helps to improve the overall safety performance of the battery. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0028] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0031] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, 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 possible implementation.

[0032] The direction parallel to the direction of the electrode plate is defined as longitudinal, and the direction perpendicular to the direction of the electrode plate is defined as transverse.

[0033] The composite electrode preparation apparatus of this application includes a shaping roller assembly, an electrode unwinding mechanism, a solid electrolyte membrane unwinding mechanism, and a composite electrode winding mechanism. The shaping roller assembly includes a first shaping roller and a second shaping roller symmetrically arranged on both sides of the electrode electrode; at least one of the first and second shaping rollers is equipped with a heating mechanism, and the connecting line between the axes of the first and second shaping rollers is perpendicular to the conveying direction of the electrode electrode.

[0034] In some embodiments, the temperature range of the shaping roller assembly equipped with the heating mechanism is 100-300°C, including but not limited to 100°C, 150°C, 200°C, 250°C, and 300°C. Preferably, it is 150-200°C.

[0035] It is understood that this application does not impose any particular limitations on the heating mechanism. The heating mechanism can be located inside the shaping roller assembly or on the outer surface of the shaping roller assembly. The heating mechanism can adopt contact heating, forced air heating, or radiant heating. Specifically, heating components such as heating plates, heating wires, and hot air blowers can be used for heating.

[0036] It is understandable that the composite electrode preparation device also includes an electrode unwinding mechanism, a composite electrode winding mechanism, and a solid electrolyte membrane unwinding mechanism;

[0037] The electrode unwinding mechanism is located upstream of the shaping roller assembly. It is used to unwind the electrode sheet and then transport the electrode sheet through the gap between the first shaping roller and the second shaping roller.

[0038] The composite electrode winding mechanism is located downstream of the shaping roller assembly. It is used to provide tension to the electrode sheet in the direction of electrode sheet movement and to receive the composite electrode sheet obtained after being rolled by the shaping roller assembly to complete the winding action.

[0039] The solid electrolyte membrane unwinding mechanism is located upstream of the shaping roller assembly, and more specifically, between the electrode unwinding mechanism and the shaping roller assembly. The solid electrolyte membrane unwinding mechanism is used to unwind the solid electrolyte membrane and then transport it through the gap between the first and second shaping rollers; more specifically, it allows the solid electrolyte membrane to pass between the electrode sheet and the shaping roller assembly.

[0040] This application does not impose any special requirements on the specific structure and form of the winding structure and unwinding mechanism. Any known winding and unwinding structure can be used in this application without departing from the inventive concept of this application.

[0041] In some embodiments, there are two solid electrolyte membrane unwinding mechanisms, located on both sides of the electrode sheet unwinding mechanism. The solid electrolyte membrane is then conveyed so that the two solid electrolyte membranes pass through the gap between the first shaping roller and the second shaping roller, and the electrode sheet is located between the two solid electrolyte membranes.

[0042] Optionally, two solid electrolyte membrane unwinding mechanisms are symmetrically arranged on both sides of the electrode sheet unwinding mechanism.

[0043] In some embodiments, the apparatus for preparing composite electrodes also includes a substrate winding mechanism.

[0044] When a substrate is disposed on a solid electrolyte membrane, the substrate covers the side of the solid electrolyte membrane away from the electrode sheet. After the electrode sheet and the solid electrolyte membrane are rolled together by a shaping roller assembly to form a composite electrode sheet, the substrate needs to be separated. This separation is achieved by a substrate winding mechanism located downstream of the shaping roller assembly. During the separation process, the substrate winding mechanism applies tension to the substrate of the solid electrolyte membrane, causing the substrate to separate from the composite electrode sheet, and, if necessary, winding up the substrate.

[0045] The number of substrate winding mechanisms corresponds to the number of solid electrolyte membrane unwinding mechanisms.

[0046] In some embodiments, the composite electrode preparation apparatus includes a guide roller; the guide roller causes the solid electrolyte membrane to reside on the shaping roller for a longer time than the electrode sheet resides on the shaping roller.

[0047] Understandably, guide rollers are used to guide the solid electrolyte membrane. Guide rollers may also be provided between the shaping roller assembly and the substrate winding mechanism to guide the substrate of the solid electrolyte membrane separated from the composite electrode.

[0048] It is understandable that the solid electrolyte membrane and the electrode sheet can remain on the shaping roller assembly either on the first shaping roller or the second shaping roller.

[0049] Based on the structure of the composite electrode preparation apparatus, the composite electrode preparation method of this application includes the following steps: unwinding an electrode sheet through an electrode sheet unwinding mechanism and conveying the electrode sheet to a composite electrode sheet winding mechanism, so that the electrode sheet passes through the gap between the first shaping roller and the second 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 reaches the shaping roller assembly for preheating and passes through the gap between the shaping roller assembly and the electrode sheet; then heating and rolling the electrode sheet and the preheated solid electrolyte membrane together through the first shaping roller and the second shaping roller; during the rolling process, an elastic element is provided between the shaping roller assembly and the solid electrolyte membrane; finally, downstream of the shaping roller assembly, the composite electrode sheet is received by the composite electrode sheet winding mechanism.

[0050] In some embodiments, at least one of the first and second shaping rollers is provided with a heating mechanism. After the solid electrolyte membrane is heated by the shaping roller assembly provided with the heating mechanism, it rotates a certain angle with the shaping roller assembly and enters the gap between the shaping roller assembly and the electrode plate.

[0051] In some embodiments, after the electrode sheet is bonded to the solid electrolyte membrane, it reaches a shaping roller assembly equipped with a heating mechanism for heating. Then, after rotating a certain angle with the shaping roller assembly, it enters the gap between the first shaping roller and the second shaping roller to receive rolling pressure. The contact time between the electrode sheet and the shaping roller assembly is less than the contact time between the solid electrolyte membrane and the shaping roller assembly. Therefore, the temperature of the electrode sheet is lower than the temperature of the solid electrolyte membrane during the composite process.

[0052] Alternatively, after the electrode sheet reaches the shaping roller assembly surrounded by a solid electrolyte membrane, it simultaneously undergoes heating and rolling composite processes from the shaping roller assembly. Therefore, the contact time between the electrode sheet and the shaping roller assembly is shorter than the contact time between the solid electrolyte membrane and the shaping roller assembly, and the temperature of the electrode sheet is lower than the temperature of the solid electrolyte membrane during the composite process.

[0053] In some embodiments, the composite electrode includes an electrode sheet and a solid electrolyte membrane, and the first or second shaping roller in the shaping roller assembly, which is located on the same side of the electrode sheet as the solid electrolyte membrane, is provided with a heating mechanism.

[0054] In some embodiments, the composite electrode includes an electrode sheet and solid electrolyte membranes located on both sides of the electrode sheet. After transporting the electrode sheet, the solid electrolyte membrane is unwound by two solid electrolyte membrane unwinding mechanisms located on both sides of the electrode sheet unwinding mechanism and fed into the shaping roller assembly. This allows the two solid electrolyte membranes to reach the first shaping roller and the second shaping roller respectively for heating, and then pass through the gap between the first and second shaping rollers; both the first and second shaping rollers are equipped with heating mechanisms. In the gap between the first and second shaping rollers, the two solid electrolyte membranes, the electrode sheet located between the two solid electrolyte membranes, and the elastic element located on the outer side of the two solid electrolyte membranes are bonded together in pairs. Under the rolling pressure of the shaping roller assembly, the solid electrolyte membranes are composited on both sides of the electrode sheet, thus obtaining the composite electrode.

[0055] In some embodiments, the solid electrolyte membrane is formed independently, meaning that the solid electrolyte membrane can be formed and maintain its integrity without the aid of a substrate. In this case, after the electrode sheet and the solid electrolyte membrane enter the gap of the shaping roller assembly, a composite electrode sheet is formed under the pressure of the shaping roller assembly, and then the composite electrode sheet is wound up by the electrode sheet winding mechanism.

[0056] In some embodiments, a substrate layer is coated on the solid electrolyte membrane to provide support. The substrate is positioned on the side of the solid electrolyte membrane away from the electrode sheet as the solid electrolyte membrane is conveyed by the solid electrolyte membrane unwinding mechanism. After the solid electrolyte membrane and electrode sheet are laminated, the substrate is separated from the laminated electrode sheet. Specifically, the substrate can be received by separate substrate winding mechanisms located on either side of the laminated electrode sheet winding mechanism, with the substrate winding mechanisms situated between the shaping roller assembly and the laminated electrode sheet winding mechanism.

[0057] In some embodiments, the elastic element is an adhesive layer that surrounds and covers the outer sides of the first and second shaping rollers. As the shaping roller assembly rotates, the adhesive layer rotates with it; and when the shaping roller assembly rolls the solid electrolyte membrane and / or electrode sheet, the adhesive layer provides a buffering effect on the solid electrolyte membrane and / or electrode sheet, allowing the solid electrolyte membrane to better cover one or both sides of the electrode sheet, while simultaneously improving the uniformity of the transverse thickness of the rolled electrode sheet.

[0058] By setting one or more guide rollers between the solid electrolyte membrane unwinding mechanism and the shaping roller assembly, the solid electrolyte membrane first reaches the shaping roller assembly equipped with a heating mechanism for preheating, and then enters the gap between the shaping roller assembly and the electrode sheet to undergo the roll pressing and bonding process.

[0059] In some embodiments, the elastic element is a protective film. The protective film is unwound by two protective film unwinding mechanisms located on the side of the solid electrolyte membrane unwinding mechanism away from the electrode sheet. The protective film unwinding mechanism conveys the protective film to the shaping roller assembly so that the two protective films pass through the gap between the first shaping roller and the second shaping roller 32, respectively. In the gap between the first shaping roller and the second shaping roller, the protective film, the solid electrolyte membrane, the electrode sheet, the solid electrolyte membrane, and the protective film are sequentially distributed and bonded together in pairs. Under the rolling pressure of the shaping roller assembly, the solid electrolyte membrane is composited on both sides of the electrode sheet, thereby obtaining a composite electrode sheet.

[0060] Before rolling, the solid electrolyte membrane is preheated to soften it to a certain extent, improving its ductility. The heating time for the electrode sheet is shorter than that for the solid electrolyte membrane, thus limiting its ductility and helping to maintain its longitudinal width. During rolling, the shaping roller assembly applies tension to both the electrode sheet and the solid electrolyte membrane. Two protective films, located between the shaping roller assembly and the solid electrolyte membrane, act as a buffer, ensuring that the force on each point of the electrode sheet and the solid electrolyte membrane is relatively uniform. This results in a composite electrode where the solid electrolyte membrane almost completely covers the electrode sheet, leading to better bonding between the electrode sheet and the solid electrolyte membrane, improved consistency in the transverse thickness of the composite electrode, and increased compaction density.

[0061] Understandably, each guide roller can guide independently, or two or more guide rollers can be combined for guiding.

[0062] In some embodiments, the mechanical speed of the first shaping roller and the second shaping roller is 10-60 m / min, including but not limited to 10 m / min, 20 m / min, 30 m / min, 40 m / min, 45 m / min, 50 m / min, and 60 m / min.

[0063] It is understandable that a higher conveyor speed in the entire composite electrode preparation apparatus results in higher production efficiency, but excessively high speeds can easily lead to problems such as belt breakage between the conveyor electrode and the solid electrolyte membrane. This application does not impose any special requirements on the residence time of the electrode sheet and the solid electrolyte membrane within the gap of the shaping roller assembly. Any adjustments to the residence time made without inventive effort, provided they do not contradict the inventive concept of this application, should be understood as falling within the scope of protection of this application.

[0064] In some implementations, the linear speeds of the first and second shaping rollers are kept consistent, as are the unwinding linear speeds of the electrode sheet unwinding mechanism and the winding linear speeds of the composite electrode sheet winding mechanism, thereby improving the consistency of the entire composite electrode sheet rolling process and enhancing the consistency of the composite electrode sheet.

[0065] The present invention provides a method for preparing composite electrodes using the aforementioned composite electrode preparation apparatus, comprising:

[0066] S10: Preheat the solid electrolyte membrane via the shaping roller assembly;

[0067] S20: The electrode sheet and the preheated solid electrolyte membrane are heated and rolled together by a shaping roller assembly to obtain a composite electrode sheet.

[0068] An elastic element is provided between the shaping roller assembly and the solid electrolyte membrane pressed onto the electrode sheet.

[0069] The preparation method of this application utilizes an elastic element to provide a buffer for the rolling process. On the one hand, it avoids the problem of low composite efficiency caused by the poor deformation resistance of rigid rollers; on the other hand, it avoids the adverse effects of the electrode sheet being thicker in the middle and thinner at both ends on the rolling composite process. Furthermore, the heating time of the solid electrolyte membrane by the shaping roller assembly is longer than the heating time of the electrode sheet by the shaping roller assembly, resulting in the temperature of the electrode sheet being lower than that of the solid electrolyte membrane during rolling. This further leads to the solid electrolyte membrane having better ductility than the electrode sheet. Under these circumstances, after rolling, the solid electrolyte membrane can better cover the surface of the electrode sheet, resulting in better bonding between the active material layer in the electrode sheet and the solid electrolyte membrane, and also effectively improving the consistency of the lateral thickness of the composite electrode sheet.

[0070] The composite process in this application is carried out under dry conditions, which differs from traditional wet electrode preparation methods. Traditional wet composite electrode preparation involves first preparing a solid electrolyte slurry, then coating the solid electrolyte slurry onto the electrode sheet, or vice versa, preparing an electrode slurry and then coating the electrode slurry onto a solid electrolyte membrane. This application's preparation process does not use solvents, eliminating the cumbersome subsequent drying step and effectively reducing production costs.

[0071] It is understood that dry process refers to the preparation of related electrode sheets and electrolyte membranes without the addition of solvents; the technical solutions that may use trace amounts of liquid lubricants or other liquid additives during the rolling process should still be within the scope of protection of this application.

[0072] In some embodiments, both the electrode sheets and the solid electrolyte membrane are prepared by a dry process.

[0073] In some embodiments, at least one of the electrode sheet and the solid electrolyte membrane is prepared by a dry process.

[0074] In some embodiments, both the electrode sheets and the solid electrolyte membrane are prepared by a wet process.

[0075] It is understandable that electrode sheets and solid electrolyte membranes are preferably prepared under dry conditions, so that solvents are no longer needed in the entire electrode preparation process.

[0076] It is understandable that the preparation process of the electrode sheet and the solid electrolyte membrane is independent of the preparation process of the composite electrode. That is, if the wet process is used, the electrode sheet goes through the processes of coating, drying and rolling.

[0077] In some embodiments, the electrode sheet is a positive electrode sheet. Positive electrode materials, especially high-nickel ternary materials with high energy density, are prone to undesirable side reactions with electrolytes, especially non-aqueous electrolytes. These side reactions cause a decrease in battery performance and create potential safety hazards. Composite solid electrolyte layers on the surface of the positive electrode are beneficial to improving battery safety.

[0078] The positive electrode sheet comprises an active material layer and a current collector layer. In the dry preparation of the positive electrode sheet, the active material, conductive agent, and binder are first stirred to obtain a positive electrode mixture; this mixture is then subjected to fibrous treatment to obtain a fibrous mixture of the positive electrode; the fibrous mixture of the positive electrode and the current collector layer are then combined by roll forming to obtain the positive electrode sheet. In some embodiments, the fibrousization methods include, but are not limited to, air jet milling, high-speed stirring, mechanical fusion, and twin-screw extrusion.

[0079] The positive electrode active material layer is formed of a positive electrode active material containing one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. The positive electrode active material layer has a thickness greater than or equal to about 1 μm and less than or equal to about 1,000 μm.

[0080] The positive electrode active material is one of layered oxides, spinel, and polyanionic materials. For example, layered oxides (e.g., rock salt layered oxides) contain one or more lithium-based positive electrode active materials selected from: LiCoO2 (LCO), LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi 1-x-y Co x Al y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi x Mn 1-x O2 (where 0 ≤ x ≤ 1), and Li 1+x MO2 (where M is one of Mn, Ni, Co, and Al and 0 ≤ x ≤ 1). Spinel contains one or more lithium-based cathode active materials selected from the following: LiMn2O4 (LMO) and LiNi. x Mn 1.5O4. Olivine type comprises one or more lithium-based cathode active materials, LiMPO4 (where M is at least one of Fe, Ni, Co, and Mn). Polyanionic cations comprise, for example, phosphates such as LiV2(PO4)3 and / or silicates such as LiFeSiO4.

[0081] In some embodiments, one or more lithium-based cathode active materials may optionally be coated (e.g., by LiNbO3 and / or Al2O3) and / or may be doped (e.g., by magnesium (Mg)). Furthermore, in some embodiments, one or more lithium-based cathode active materials may optionally be mixed with one or more conductive materials that provide electronic conduction pathways and / or at least one polymeric binder material that improves the structural integrity of the cathode. For example, the cathode active material layer may comprise more than or equal to about 30% by weight and less than or equal to about 99% by weight of one or more lithium-based cathode active materials; more than or equal to about 0% by weight and less than or equal to about 30% by weight of conductive materials; and more than or equal to about 0% by weight and less than or equal to about 20% by weight of binder.

[0082] In some embodiments, the adhesive includes polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof.

[0083] In some embodiments, the conductive material may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0084] It is understood that the examples of positive electrode active materials, binders, and conductive materials mentioned above are merely illustrative. Without departing from the inventive concept of this application, any known positive electrode active material, binder, or conductive material can be used in this application. Furthermore, the addition of known additives based on actual usage requirements should also be considered within the scope of protection of this application.

[0085] In some implementations, the current collector layer contains active material layers on both sides.

[0086] In some implementations, the current collector layer may be a metal foil or a composite current collector.

[0087] For example, the metal foil may be aluminum foil.

[0088] 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.

[0089] In some implementations, the electrode is a negative electrode.

[0090] The negative electrode sheet is formed from a lithium host material (e.g., a negative electrode active material) capable of being used as the negative terminal of a lithium-ion battery. In various aspects, the negative electrode sheet may be defined by a variety of negative electrode active material particles. Such negative electrode active material particles may be disposed in one or more layers to define the three-dimensional structure of the negative electrode. In some embodiments, the negative electrode may also include an electrolyte, such as electrolyte particles (not shown).

[0091] In some embodiments, the negative electrode may be a lithium-based negative electrode active material, which contains, for example, lithium metal and / or lithium alloys.

[0092] The negative electrode can be a silicon-based negative electrode active material, which includes, for example, silicon alloys, silicon oxide, or combinations thereof, and in some cases, it can also be mixed with graphite.

[0093] The negative electrode can be a carbon-based negative electrode active material, which includes one or more of graphite, graphene, carbon nanotubes (CNTs), and combinations thereof.

[0094] The negative electrode may also include one or more negative electrode active materials that accept lithium, such as lithium titanium oxide (Li4Ti5O). 12 One or more transition metals (e.g., tin (Sn)), one or more metal oxides (e.g., vanadium oxide (V2O5), tin oxide (SnO), titanium dioxide (TiO2)), titanium niobium oxide (TixNbyOz, where 0≤x≤2, 0≤y≤24 and 0≤z≤64), metal alloys (e.g., copper-tin alloy (Cu6Sn5)), and one or more metal sulfides (e.g., iron sulfide (FeS)).

[0095] Alternatively, the negative electrode active material in the negative electrode sheet may be doped with one or more conductive materials that provide an electron conduction path and / or at least one polymer binder material that improves the structural integrity of the negative electrode. For example, the negative electrode active material may be doped with binders such as: poly(tetrafluoroethylene) (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof. The conductive material may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, superP, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc.

[0096] The negative electrode may include more than or equal to about 50% by weight and less than or equal to about 99% by weight of negative electrode active material, optionally more than or equal to about 0% by weight and less than or equal to about 60% by weight of solid electrolyte, optionally more than or equal to about 0% by weight and less than or equal to about 15% by weight of conductive material, and optionally more than or equal to about 0% by weight and less than or equal to about 10% by weight of binder.

[0097] In some embodiments, the solid electrolyte membrane includes a solid electrolyte and a binder.

[0098] Preferably, the solid electrolyte membrane comprises a solid electrolyte, a binder, and a lithium salt.

[0099] In preparing a solid electrolyte membrane, the solid electrolyte, binder and lithium salt are first stirred and mixed. After the mixture is fiberized, a fiberized solid electrolyte mixture is obtained. The fiberized solid electrolyte mixture is then rolled to obtain a solid electrolyte membrane.

[0100] In some embodiments, the solid electrolyte is an inorganic solid electrolyte, including one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, boride solid electrolytes, and nitride solid electrolytes.

[0101] Oxide solid electrolytes include one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, one or more garnet ceramics include, but are not limited to, Li. 6.5 La3Zr 1.75 Te 0.25 O12 , Li7La3Zr2O 12 , Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 , Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 , Li 6.25 Al 0.25 La3Zr2O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12 or more than one of the following. One or more LISICON-type oxides include, but are not limited to, Li 14 Zn(GeO4)4, Li 3+x (P 1-x Si x )O4 (where 0 < x < 1), Li 3+x Ge x V 1-x O4 (where 0 < x < 1). One or more NASICON-type oxides can be defined by LiMM′(PO4)3, where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example, in certain variations, one or more NASICON-type oxides include, but are not limited to, Li 1+x Al x Ge 2-x (PO4)3 (LAGP) (where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4)3 (LATP) (where 0 ≤ x ≤ 2), Li 1+ x Y x Zr 2-x (PO4)3 (LYZP) (where 0 ≤ x ≤ 2), Li 1.3 Al 0.3 Ti[[ID=​​​​​​​​​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), one or more of these

[0102] 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 , Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li9.54 Si 1.74 P 1.44 S 11.7 C l0.3 、 (1-x) P2S 5-x One or more of Li2S (where 0.5 ≤ x ≤ 0.7).

[0103] Halide solid electrolytes include, but are not limited to, Li2CdC l4 、Li2MgC l4 、Li2Cd I4 、Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1).

[0104] Boride solid electrolytes include, but are not limited to, one or more of Li2B4O7, Li2O-(B2O3)-(P2O5).

[0105] Nitride solid electrolytes include, but are not limited to, one or more of Li3N, Li7PN4, LiSi2N3, LiPON.

[0106] 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.

[0107] 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.

[0108] 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).

[0109] In some embodiments, lithium salts include, but are not limited to, lithium hexafluorophosphate (LiPF6); lithium perchlorate (LiClO4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium difluorooxalate borate (LiBF2(C2O4))(LiODFB), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalate)borate (LiB(C2O4)2)(LiBOB), lithium tetrafluorooxalate phosphate (LiPF4(C2O4))(LiFOP), lithium nitrate (LiNO3), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonylimide) (LITFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonylimide) (LiN(FSO2)2)(LIFSI), and combinations thereof. In some variations, the lithium salt is selected from one or more of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonylimide) (LiTFSI)(LiN(CF3SO2)2), lithium bis(fluorosulfonylimide) (LiN(FSO2)2)(LiFSI), lithium fluoroalkylphosphonate (LiFAP), and lithium phosphate (Li3PO4).

[0110] It is understood that the terms mentioned above, including oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, nitride solid electrolytes, polymer solid electrolytes, etc., are all known in the art. The details of the above materials are merely illustrative examples and not a limitation on the scope of protection. Without departing from the inventive concept of this application, any known type of solid electrolyte can be used in this application.

[0111] In some embodiments, the thickness of the solid electrolyte membrane is 1-30 μm. Solid electrolyte membranes can effectively improve the safety performance of batteries, 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.

[0112] Preferably, the thickness of the solid electrolyte membrane is 3-30 μm; more preferably, it is 3-20 μm; more preferably, it is 5-15 μm.

[0113] This application does not specifically limit the type of substrate. Without departing from the inventive concept of this application, any known material that provides a certain supporting function, facilitates the formation of electrolyte material film, and can be separated from the solid electrolyte membrane after rolling can be used in this application. This is merely an illustrative example and not a limitation on the scope of protection. The substrate is selected from one or more of the following: silicone oil release film, fluorine release film, PET film, PP film, PE film, PE / PP film, PP / PE / PP film, PE / PP / PE film, and non-silicone release film.

[0114] This application also provides a composite electrode sheet, which is prepared according to the above-described method for preparing composite electrodes.

[0115] This application also provides a solid-state battery, which includes the composite electrode provided above.

[0116] In some implementations, the electrode plates and solid electrolyte membranes may also be procured.

[0117] The embodiments of the present invention will be described in more detail below through examples. However, the embodiments of the present invention are not limited to these examples.

[0118] Example 1

[0119] 1. Preparation of positive electrode sheet

[0120] Lithium manganese oxide was selected as the positive electrode active material, Ketjen black as the conductive agent, and PTFE as the binder. These substances were mixed and stirred using a high-speed stirrer to obtain a positive electrode mixture. This mixture was then subjected to a fibrous treatment using an air jet mill to obtain a fibrous positive electrode mixture, i.e., the positive electrode active material layer. This positive electrode active material layer was then combined with a current collector through roll forming to obtain the positive electrode sheet.

[0121] 2. Preparation of solid electrolyte membranes

[0122] LGPS was selected as the solid electrolyte and polytetrafluoroethylene as the binder. The above substances were mixed and stirred using a high-speed mixer to obtain a solid electrolyte mixture. Then, the mixture was subjected to fiberization treatment by air jet milling to obtain a fiberized solid electrolyte mixture. The fiberized solid electrolyte mixture was then rolled to obtain a solid electrolyte membrane.

[0123] 3. Preparation of composite positive electrode sheet

[0124] The positive electrode sheet is composited with two layers of solid electrolyte membrane, so that the solid electrolyte membrane is simultaneously composited on both sides of the positive electrode active material layer.

[0125] The solid electrolyte membrane starts from the solid electrolyte membrane unwinding mechanism, passes through the first guide roller, and then meets and adheres to the protective film at the second guide roller. The protective film starts from the protective film unwinding mechanism, adheres to the solid electrolyte membrane, and then moves together to the first or second shaping roller. The solid electrolyte membrane and the protective film rotate a certain angle with the shaping roller assembly and then come into contact with the positive electrode sheet, passing through the gap between the first and second shaping rollers, or more specifically, through the gap between the shaping roller assembly and the positive electrode sheet. The solid electrolyte membrane and the protective film are heated during the rotation of the shaping roller assembly.

[0126] Then, under the pressure of the first and second shaping rollers, the positive electrode sheet is laminated with two layers of solid electrolyte membrane. During the movement of the electrode sheet, solid electrolyte membrane, and protective film between the first and second shaping rollers, they are all heated. The composite electrode sheet then moves towards the composite electrode sheet winding mechanism, where it is received and wound up, resulting in a composite electrode sheet with solid electrolyte membrane laminated on both sides of the positive electrode sheet.

[0127] After the protective film and substrate separate from the composite electrode sheet through the gap between the first and second shaping rollers, they rotate at a certain angle along with either the first or second shaping roller. Then, under the action of the protective film winding mechanism and the solid electrolyte membrane winding mechanism, the protective film and substrate move towards the third guide roller and rotate around it at a certain angle before separating. The protective film is received and wound by the protective film winding mechanism, and the substrate is received and wound by the substrate winding mechanism.

[0128] Example 2

[0129] 1. Preparation of positive electrode sheet

[0130] Lithium manganese oxide was selected as the positive electrode active material, Ketjen black as the conductive agent, and PTFE as the binder. These substances were mixed and stirred using a high-speed stirrer to obtain a positive electrode mixture. This mixture was then subjected to a fibrous treatment using an air jet mill to obtain a fibrous positive electrode mixture, i.e., the positive electrode active material layer. This positive electrode active material layer was then combined with a current collector through roll forming to obtain the positive electrode sheet.

[0131] 2. Preparation of solid electrolyte membranes

[0132] LATP was selected as the solid electrolyte, polytetrafluoroethylene as the binder, and LiPF6 as the lithium salt. These substances were mixed and stirred using a high-speed stirrer to obtain a solid electrolyte mixture. This mixture was then subjected to a fiberization process using an air jet mill to obtain a fiberized solid electrolyte mixture. Finally, this fiberized solid electrolyte mixture was rolled to obtain a solid electrolyte membrane.

[0133] 3. Preparation of composite positive electrode sheet

[0134] Using a composite electrode preparation apparatus with a protective film, a positive electrode is composited with two layers of solid electrolyte membrane, so that the solid electrolyte membrane is simultaneously composited on both sides of the positive electrode active material layer. The protective film is a PE-based nonwoven fabric. Unlike Example 1, the substrate separates only after traveling a certain distance with the composite electrode.

[0135] The solid electrolyte membrane starts from the solid electrolyte membrane unwinding mechanism, passes through the first guide roller, and then meets and adheres to the protective film at the second guide roller. The protective film starts from the protective film unwinding mechanism, adheres to the solid electrolyte membrane, and then moves together to the first or second shaping roller. The solid electrolyte membrane and the protective film rotate a certain angle with the shaping roller assembly and then come into contact with the positive electrode sheet, passing through the gap between the first and second shaping rollers, or more specifically, through the gap between the shaping roller assembly and the positive electrode sheet. The solid electrolyte membrane and the protective film are heated during the rotation of the shaping roller assembly.

[0136] Then, under the pressure of the first and second shaping rollers, the positive electrode sheet is laminated with two layers of solid electrolyte membrane. During the movement of the electrode sheet, solid electrolyte membrane, and protective film between the first and second shaping rollers, they are all heated. The composite electrode sheet then moves towards the composite electrode sheet winding mechanism, where it is received and wound up, resulting in a composite electrode sheet with solid electrolyte membrane laminated on both sides of the positive electrode sheet.

[0137] After the protective film leaves the gap between the first and second shaping rollers, it separates from the composite electrode and rotates at a certain angle with either the first or second shaping roller. It is then received and wound by the protective film winding mechanism. The substrate moves a distance along with the composite electrode towards the composite electrode winding mechanism until it reaches the fifth guide roller. There, it receives the force transmitted by the substrate winding mechanism via the fourth and fifth guide rollers. At the fifth guide roller, the substrate separates from the composite electrode and is finally received and wound by the substrate winding mechanism. The substrate moves on the side of the fourth and fifth guide rollers away from the electrode.

[0138] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0139] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a composite electrode, characterized in that, The preparation method includes: The electrode sheet is conveyed by the electrode sheet unwinding mechanism, so that the electrode sheet passes through the gap in the middle of the shaping roller assembly; The solid electrolyte membrane is conveyed by a solid electrolyte membrane unwinding mechanism located on the side of the electrode sheet unwinding mechanism, so that the solid electrolyte membrane reaches the shaping roller assembly for preheating and passes through the gap between the shaping roller assembly and the electrode sheet; the shaping roller assembly includes a first shaping roller and a second shaping roller; at least one of the first shaping roller and the second shaping roller is provided with a heating mechanism; The solid electrolyte membranes located on both sides of the electrode sheet are pressed onto the electrode sheet by the first shaping roller and the second shaping roller to obtain a composite electrode sheet; During the rolling process, the temperature of the solid electrolyte membrane is higher than that of the electrode sheet.

2. The preparation method according to claim 1, characterized in that, Both the first shaping roller and the second shaping roller are equipped with a heating mechanism.

3. The preparation method according to claim 1, characterized in that, An elastic element is provided between the shaping roller assembly and the solid electrolyte membrane pressed onto the electrode sheet. The elastic element is a protective film, which is transported through the gap between the shaping roller assembly and the solid electrolyte membrane.

4. The preparation method according to claim 3, characterized in that, The protective film is a polymer film or a non-woven fabric.

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

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

7. A composite electrode, characterized in that, The composite electrode is prepared using the preparation method described in any one of claims 1 to 6.

8. A solid-state battery, characterized in that, This includes composite electrodes prepared by the preparation method according to any one of claims 1 to 6.