A dry-method positive electrode sheet, a preparation method thereof and application thereof

Abstract

The application provides a dry-method positive electrode sheet and a preparation method and application thereof. The dry-method positive electrode sheet comprises at least a positive electrode current collector, a dry-method positive electrode active layer arranged on at least one side surface of the positive electrode current collector in a thickness direction of the positive electrode current collector, and the dry-method positive electrode active layer comprises a positive electrode active material, a conductive agent and a binder. The uniformity of the binder in the dry-method positive electrode active layer is more than 95%. The dry-method positive electrode sheet and the preparation method and application thereof can reduce the risk of falling and short circuit of the dry-method positive electrode active layer, and improve the safety performance, capacity and cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to a dry-process positive electrode sheet and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries offer numerous advantages, including high voltage, high capacity, long cycle life, low self-discharge efficiency, and excellent safety. They are widely used in 3C / digital products, electric vehicles, energy storage, and other fields. The positive electrode is a crucial component of lithium-ion batteries, and its composition and structure have a decisive influence on its electrochemical performance. The positive electrode comprises a positive active material, a conductive agent, and a binder, with the binder playing a key role in securing the other positive electrode components.

[0003] Wet slurry coating is the mainstream method for preparing positive electrode sheets, but it is subject to issues such as high cost, environmental pollution, and solvent volatilization that creates gaps between the positive electrode active material and the conductive agent. Dry processes also suffer from severe powder shedding, which can lead to significant degradation in battery charge and discharge performance and capacity. Summary of the Invention

[0004] The present invention proposes a dry-process positive electrode plate and its preparation method and application. The dry-process positive electrode plate and its preparation method and application provided by the present invention can reduce the risk of shedding and short circuit of the dry-process positive electrode active layer and improve the safety performance, capacity and cycle performance of the battery.

[0005] In order to solve the above technical problems, the present invention provides a dry-process positive electrode sheet, comprising at least:

[0006] positive electrode current collector;

[0007] A dry-process positive electrode active layer is provided on at least one surface along the thickness direction of the positive electrode current collector. The dry-process positive electrode active layer comprises a positive electrode active material, a conductive agent and a binder. The uniformity of the binder in the dry-process positive electrode active layer is above 95%.

[0008] In one embodiment of the present invention, the binder in the dry-process positive electrode active layer is in the form of nanofibers, and the diameter d of the nanofibers is 50 4nm-10nm, d 90 / d 10 ≤1.5, where d 50 is the diameter of the nanofibers when the number of nanofibers increases from small to large to 50%, d 10 is the diameter of the nanofibers when the number of nanofibers from small to large accumulates to 10%, d 90 It is the diameter when the cumulative number of the nanofiber diameters from small to large reaches 90%.

[0009] In one embodiment of the present invention, the content of the binder in the dry-process positive electrode active layer is 0.2 wt %-1 wt %.

[0010] In one embodiment of the present invention, the binder includes one or more of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, ethylene-octene copolymer or polyimide.

[0011] In one embodiment of the present invention, the positive electrode active material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide or lithium-rich manganese-based oxide;

[0012] And / or, the conductive agent is selected from at least one of graphite, graphene, carbon black, carbon fiber and carbon nanotubes.

[0013] The present invention also provides a method for preparing a dry-process positive electrode sheet, which comprises at least the following steps:

[0014] Sieving binder particles with a preset median particle size;

[0015] Mixing the positive electrode active material, the conductive agent, and the binder particles to obtain a mixed material;

[0016] performing a fibrillation treatment on the mixed material to obtain a fibrillated material;

[0017] Cooling the fibrillated material to a target temperature at a preset rate while applying shear to obtain an intermediate product;

[0018] Crushing and granulating the intermediate product to obtain a dry-process positive electrode material;

[0019] The dry-process positive electrode material is formed into a film by continuous rolling with multiple rollers to obtain a dry-process positive electrode active layer;

[0020] The dry-process positive electrode active layer is compounded with the positive electrode current collector to obtain a dry-process positive electrode sheet.

[0021] In one embodiment of the present invention, the preset median particle size of the binder particles is X1 μm, and the diameter d of the nanofibers in the dry-process positive electrode active layer is 50 If it is X2nm, then the relationship is: -5≤0.2X1-X2≤5;

[0022] And / or, the binder particles have a preset median particle size of 20 μm to 50 μm.

[0023] In one embodiment of the present invention, the binder particles are sieved at a preset temperature, wherein the preset temperature is 5° C.-20° C.;

[0024] The fibrillation includes a first stage, a second stage and a third stage. In the first stage, the treatment temperature is 20°C-40°C, the stirring linear speed is 20m / s-30m / s, and the stirring time is 10min-30min; in the second stage, the treatment temperature is 60°C-80°C, the stirring linear speed is 40m / s-60m / s, and the stirring time is 10min-30min; in the third stage, the treatment temperature is 90°C-120°C, the stirring linear speed is 60m / s-70m / s, and the stirring time is 60min-120min;

[0025] The preset rate is 10°C / min-15°C / min, and the target temperature is 25°C-40°C;

[0026] During the cooling process, pulse shearing is applied, wherein one pulse shearing comprises shearing at 8 m / s-10 m / s for 4 s-6 s and shearing at 3 m / s-5 m / s for 8 s-12 s.

[0027] The present invention also provides an all-solid-state lithium-ion battery, comprising at least:

[0028] A positive electrode sheet, selected from the dry-process positive electrode sheet described above, or a dry-process positive electrode sheet obtained by the preparation method described above;

[0029] negative electrode;

[0030] The solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet.

[0031] In one embodiment of the present invention, the positive electrode plate further includes a solid electrolyte, and the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

[0032] The present invention also provides an electronic device comprising the above-mentioned all-solid-state lithium-ion battery.

[0033] In summary, the present invention proposes a dry-process positive electrode sheet and its preparation method and application. By improving the uniformity of the binder in the dry-process positive electrode active layer, it can promote the effective transmission of lithium ions and electrons while ensuring the mechanical stability of the positive electrode sheet, thereby improving the performance of the positive electrode sheet, reducing the risk of shedding and short circuit of the dry-process positive electrode active layer, improving safety performance, and thus improving the capacity and cycle performance of the battery. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0036] The technical solutions of the present invention are further described in detail below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The present invention provides a dry-process positive electrode sheet comprising at least a positive current collector and a dry-process positive electrode active layer. The dry-process positive electrode active layer is disposed on at least one surface along the thickness direction of the positive current collector. The dry-process positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder, wherein the binder uniformity in the dry-process positive electrode active layer is greater than 95%. The binder is used to connect the positive electrode active materials or between the positive electrode active materials and the conductive agent. However, the binder is an insulating material, and uneven binder distribution can lead to powder shedding or increased insulating areas, resulting in reduced ion access. The uniformity is defined as the degree of dispersion of the binder distribution within multiple detection areas of the positive electrode sheet, and the degree of dispersion is negatively correlated with the uniformity. In the dry-process positive electrode sheet provided by the present invention, by improving the uniformity of the binder in the dry-process positive electrode active layer, the efficient transmission of lithium ions and electrons can be promoted while ensuring the mechanical stability of the positive electrode sheet, thereby improving the performance of the positive electrode sheet, reducing the risk of shedding and short-circuiting of the dry-process positive electrode active layer, and enhancing safety.

[0038] In one embodiment of the present invention, the binder in the dry-process positive electrode active layer is in the form of nanofibers, and the diameter of the nanofibers is d. 50 4nm-10nm, d 90 / d 10 ≤1.5, where d 50 is the diameter of the nanofibers when the number of nanofibers increases from small to large and reaches 50%, d 10 is the diameter of the nanofibers when the number of nanofibers increases from small to large and reaches 10%, d 90The diameter of the nanofiber is cumulatively up to 90% from small to large. If the diameter of the nanofiber is too small, the cohesion will be weakened, and the strength of the fine fiber itself will be weak, resulting in a decrease in the strength of the three-dimensional network formed. On the contrary, if the diameter of the nanofiber is too large, although the cohesion is enhanced, the insulating area between the positive active materials will increase, reducing the ion transmission capacity. Therefore, a suitable nanodiameter needs to be selected to ensure sufficient cohesion to avoid a dry electrode that is too fragile, and to make the passage more and smoother, improving the ion transmission capacity. At the same time, d 90 / d 10 ≤1.5, that is, the uniformity of the diameter of the nanofiber is high, and the distribution is uniform, which is beneficial to improve the uniformity of the binder in the dry positive active layer, can avoid the ion transmission being blocked due to the local fiber being too thick, and can also avoid the local mechanical strength being insufficient due to the local fiber being too thin, thereby improving the performance of the dry positive electrode sheet.

[0039] In an embodiment of the present application, the binder includes one or more combinations of Polytetrafluoroethylene (PTFE), Ethylene-tetra-fluoro-ethylene (ETFE), Ethylene-Vinyl Acetate Copolymer (EVA), Polypropylene (PP), Polyethylene (PE), Ethylene-octene copolymer, or Polyimide (PI), etc., and the molecular weight of the binder is, for example, 6000 kg / mol-8000 kg / mol, to improve the bonding performance of the binder and the strength of the nanofiber formed. The content of the binder in the dry positive active layer is, for example, 0.2wt%-1wt%. When the content of the binder is less than 0.2wt%, the dry positive active layer cannot be formed at this time; when the content is greater than 1wt%, the content of the binder inside the dry positive active layer is too high, which will reduce the number of ion passages. Therefore, by controlling the diameter of the binder fiber, the strength of the three-dimensional nanometer network formed is ensured, and by improving the uniformity of the binder, the content of the binder can be reduced while effectively ensuring the stability of the positive electrode sheet, thereby improving the energy density of the battery.

[0040] In one embodiment of the present invention, the positive electrode active material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or a lithium-rich manganese-based oxide. In one embodiment of the present invention, the conductive agent is selected from at least one of graphite, graphene, carbon black, carbon fiber, or carbon nanotubes, and the content of the conductive agent in the dry-process positive electrode active layer is, for example, 1 wt% to 5 wt%. The carbon black is, for example, conductive carbon black (Super P), and the carbon fiber includes, for example, at least one of carbon nanofibers (CNF), vapor-grown carbon fiber (VGCF), or vapor-grown carbon nanofibers (VGCNF). In one embodiment of the present invention, the conductive agent includes, for example, carbon black and carbon fiber, and the mass ratio of carbon black to carbon fiber is, for example, 1:(0.2-1.5), or, for example, 1:1.

[0041] In one embodiment of the present invention, the dry-process positive electrode active layer further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is further selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 , Li6PS5Cl, Li3InCl6 or Li3YCl6, etc. When the dry-process positive electrode active layer includes a solid electrolyte, the mass ratio of the positive electrode active material, the solid electrolyte, the conductive agent and the binder is, for example, (64-94): (4.8-30): (1-5): (0.2-1). In one embodiment of the present invention, the areal capacity of the dry-process positive electrode sheet is, for example, 1 mAh / cm 2 -10mAh / cm 2 , areal capacity refers to the amount of charge that can be stored per unit area of ​​the electrode, usually expressed as the area carrying capacity per unit area (mAh / cm 2 )express.

[0042] In an embodiment of the present application, the positive current collector is, for example, a carbon-coated aluminum foil, and the carbon coating layer mainly comprises a conductive carbon material and a binder. The conductive carbon material comprises one or more of conductive carbon black, acetylene black, or carbon nanotubes, and the binder comprises one or more of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), or ethylene-vinyl acetate copolymer. The mass ratio of the conductive carbon material to the binder is, for example, 60-95:5-40, and the thickness of the carbon coating layer is, for example, 1-3 μm, so as to improve the conductivity between the dry positive active layer and the positive current collector. In other embodiments, the positive current collector can also use other positive current collectors commonly used in the art.

[0043] Based on the above dry positive electrode sheet, the present application further provides a preparation method of a dry positive electrode sheet, comprising at least: screening binder particles with a preset median particle size; mixing a positive active material, a conductive agent, and the binder particles to obtain a mixture; performing fibrillation treatment on the mixture to obtain a fibrillated material; cooling the fibrillated material to a target temperature at a preset rate while applying shearing to obtain an intermediate product; performing crushing and granulation treatment on the intermediate product to obtain a dry positive electrode material; forming a film of the dry positive electrode material through multi-roll continuous rolling to obtain a dry positive active layer; and compounding the dry positive active layer with a positive current collector to obtain the dry positive electrode sheet.

[0044] In an embodiment of the present application, the binder is cooled to a brittle point of -40℃, and a closed-loop heat preservation crushing device is used for grinding to obtain a ground binder. The ground binder is screened through a screen with different pore sizes to obtain binder particles with a preset median particle size. The median particle size D50 refers to the particle size value corresponding to the cumulative volume distribution percentage of 50% in the volume distribution curve. In this embodiment, the pore size of the screen is, for example, 20-60 μm, and the preset temperature is, for example, 5-20℃. Screening at the preset temperature can prevent the binder from agglomerating due to excessively high temperature, so as to obtain solid binder particles, and the preset median particle size of the obtained binder particles is, for example, 20-50 μm.

[0045] In an embodiment of the present application, the positive active material and the conductive agent are mixed to obtain a premix. Optionally, the premix further comprises the solid-state electrolyte, and the positive active material, the solid-state electrolyte and the conductive agent are mixed to obtain the premix, and the premix and the binder particles are mixed to obtain the mixture. In the process of obtaining the premix, the components of the premix are mixed more uniformly by stirring, for example, the linear speed of stirring is controlled to be 20-40 m / s, the stirring time is controlled to be 20-60 min, and the processing temperature is controlled to be 5-60℃. In the process of obtaining the mixture, the components of the mixture are mixed more uniformly by stirring, for example, the linear speed of stirring is controlled to be 5-20 m / s, the stirring time is controlled to be 20-60 min, and the processing temperature is controlled to be 5-20℃. In the process of obtaining the premix, the linear speed is increased to improve the uniformity of the mixing of the components other than the binder. In the process of obtaining the mixture, the processing temperature (for example, the temperature during stirring of the mixture is lower than the temperature during stirring of the premix) and the linear speed are controlled to avoid problems such as agglomeration or local overheating of the binder particles caused by excessively high temperature, thereby avoiding uneven dispersion of the binder particles in the mixture.

[0046] In an embodiment of the present application, the mixture is subjected to fibrillation treatment to obtain a fibrillated material. In this embodiment, the fibrillation includes a first stage, a second stage and a third stage. In the first stage, the processing temperature is for example 20-40℃, the linear speed of stirring is for example 20-30 m / s, and the stirring time is for example 10-30 min. In the second stage, the processing temperature is for example 60-80℃, the linear speed of stirring is for example 40-60 m / s, and the stirring time is for example 10-30 min. In the third stage, the processing temperature is for example 90-120℃, the linear speed of stirring is for example 60-70 m / s, and the stirring time is for example 60-120 min. Through three-stage fibrillation treatment, the synergistic effect of stepwise temperature increase and segmented speed increase and shear is controlled to avoid excessive breakage or agglomeration of the binder. Through the high linear speed and time in the third stage, the maximum uniformity that the binder can achieve is maximized, thereby converting the binder particles into nanofibers, and the nanofibers form a uniform and dense three-dimensional network structure, thereby improving the strength of the positive electrode sheet obtained subsequently. In this embodiment, due to the limitations of the manufacturing process, the d 90 / d 10 ≥1.2.

[0047] In one embodiment of the present invention, after the fibrillation treatment step, the fibrillated material is cooled to a target temperature at a preset rate, for example, the preset rate is 10°C / min-15°C / min, and the target temperature is, for example, 25°C-40°C. During the cooling process, shearing is applied simultaneously to obtain an intermediate product. In this embodiment, the shearing is, for example, pulse shearing, and one pulse shearing includes shearing at 8m / s-10m / s for 4s-6s and shearing at 3m / s-5m / s for 8s-12s. Through rapid cooling and pulse shearing, the fiber structure can be locked to avoid fiber shrinkage caused by natural cooling, thereby stabilizing the size and distribution state of the nanofibers and obtaining a highly uniform binder distribution. At the same time, the d of the nanofibers formed by the binder can be reduced by step-by-step heating, segmented speed-up shearing, rapid cooling and pulse shearing. 90 / d 10 , improving the uniformity of nanofiber diameter.

[0048] In one embodiment of the present invention, the intermediate product is crushed and granulated to obtain a dry cathode material, and the dry cathode material is formed into a film by multi-roll continuous rolling and thinned to a set surface capacity, for example, 1 mAh / cm 2 -10mAh / cm 2 , obtaining a dry-process positive electrode active layer. The dry-process positive electrode active layer is then composited with the positive electrode current collector to obtain a dry-process positive electrode sheet. For example, the dry-process positive electrode active layer is bonded to the carbon-coated layer of the positive electrode current collector and composited at a temperature of, for example, 20°C to 100°C and under a pressure of, for example, 0.8 tons to 1.2 tons. By manipulating the parameters used in preparing the dry-process positive electrode sheet, the components in the dry-process positive electrode active layer are more evenly distributed, and the binder fibrillation effect is enhanced, thereby producing a dry-process positive electrode sheet with improved performance, thereby increasing the battery capacity.

[0049] In one embodiment of the present invention, the median particle size of the binder particles is X1 μm, and the diameter d of the nanofibers in the dry-process positive electrode active layer is 50=X2nm, satisfying the relationship: -5≤0.2X1-X2≤5. That is, when the median particle size of the binder particles is smaller, under the above preparation conditions, the diameter of the binder nanofibers obtained in the dry-process positive electrode active layer is finer, and the distribution uniformity of the nanofibers is greater, but the cohesion is low, which will reduce the performance of the battery. It is necessary to increase the binder content to improve the cohesion of the dry-process positive electrode plate. When the median particle size of the binder particles is larger, the diameter of the obtained binder nanofibers is larger. At this time, the cohesion of the dry-process positive electrode plate is sufficient. It is necessary to reduce the binder content to a lower level to improve the ion transmission capacity of the dry-process positive electrode plate. As the median particle size of the binder particles is smaller, the diameter of the obtained binder nanofibers is finer, the strength of a single nanofiber is reduced, the three-dimensional network strength is insufficient, and the overall cohesion of the plate is reduced. In this embodiment, the uniformity of the binder in the dry-process positive electrode active layer is, for example, 95%-98%. That is, by controlling the particle size of the binder particles, the binder distribution between the positive electrode active materials can be made finer, and the increased ion pathways can improve the performance of the dry-process positive electrode sheet. At the same time, by controlling the particle size and content of the binder to meet a certain range, a dry-process all-solid-state positive electrode with good mechanical properties and efficient ion transport can be prepared.

[0050] The present invention also provides an all-solid-state lithium-ion battery comprising a positive electrode sheet, a negative electrode sheet, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet is selected from the dry-process positive electrode sheet described above. In the present invention, the all-solid-state battery is, for example, a primary battery or a secondary battery, and the secondary battery is, for example, a pouch cell, a prismatic cell, or a cylindrical cell. The present invention does not impose any specific restrictions on the type or type of the all-solid-state battery.

[0051] In one embodiment of the present invention, the negative electrode plate is, for example, an indium plate, a lithium plate, an aluminum plate, or an alloy plate composed of at least two of the above metals. In other embodiments of the present invention, the negative electrode plate further comprises, for example, a negative electrode current collector and a negative electrode active layer coated on at least one surface of the negative electrode current collector. The negative electrode current collector is, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, or a stainless steel current collector, and the negative electrode active layer comprises a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder. The ratio of the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder can be selected according to actual needs. In this embodiment, the negative electrode active material is selected from graphite materials, silicon materials, or a composite material composed of the two. The graphite material includes at least one of natural graphite or artificial graphite. Natural graphite includes at least one of block graphite, flake graphite, or earthy graphite. Artificial graphite includes at least one of single crystal graphite, polycrystalline graphite, pyrolytic graphite, or graphite fiber. Silicon materials include but are not limited to silicon, silicon-carbon materials, and silicon-oxygen materials (SiO x, 0 <x<2)。负极导电剂例如选自Super p、乙炔黑、科琴黑、碳纳米管或石墨烯等中的至少一种,负极粘结剂例如选自聚丙烯、聚丙烯酸酯、聚乙烯醚、聚甲基丙烯酸甲酯、聚六氟丙烯或丁苯橡胶等中的至少一种。负极活性层可以通过干法或湿法进行制备,本申请不作具体限制。

[0052] In one embodiment of the present invention, the solid electrolyte layer includes a solid electrolyte, and the solid electrolyte is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte, and is selected from Li7La3Zr2O 12 、Li 13 Al3Ti 17 (PO4)3、Li 10 GeP2S 12 At least one of Li₆PS₅Cl₆, Li₃InCl₆, or Li₃YCl₆ is used. The solid electrolyte is pressed at, for example, 90 MPa-150 MPa to form a solid electrolyte layer. The dry-process positive electrode sheet, solid electrolyte layer, and negative electrode sheet are sequentially placed into a mold for assembly. After assembly, the pressure is applied to 100 MPa and the nuts at the top of the columns are tightened to maintain constant pressure, resulting in an all-solid-state lithium-ion battery. The assembly process is performed under an argon atmosphere or vacuum.

[0053] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0054] Example 1

[0055] Screening of binder particles: PTFE was cooled to its brittle point of -40°C and ground using a closed-circuit, temperature-controlled pulverization device. The D50 value after grinding was controlled to ≤50 μm to obtain the ground PTFE. The ground PTFE was sieved through a 40 μm sieve, and the PTFE particles that passed through the sieve were collected. The PTFE particles that passed through the sieve were then sieved through a 30 μm sieve, and the PTFE particles that did not pass through the sieve were collected. The median PTFE particle size was 36 μm. The sieving temperature was 10°C. The binder raw material was sourced from Daikin Fluorochemicals (China) Co., Ltd., model F106C, with a molecular weight of 6000 kg / mol.

[0056] Preparation of dry positive electrode: LiNi 0.8 Co 0.1 Mn 0.1O2, Li6PS5Cl, Super p, and VGCF were mixed to obtain a premix, stirred at a linear speed of 30 m / s, stirred for 30 minutes, and treated at a temperature of 25°C to obtain a premix. The premix was then mixed with binder particles to obtain a mixture, stirred at a linear speed of 15 m / s, stirred for 30 minutes, and treated at a temperature of 10°C to obtain a mixture. The mixture was subjected to a fiberization treatment to obtain a fibrillated material. The first stage was treated at a temperature of 25°C, a linear speed of 20 m / s, and stirred for 10 minutes; the second stage was treated at a temperature of 80°C, a linear speed of 50 m / s, and stirred for 10 minutes; and the third stage was treated at a temperature of 120°C, a linear speed of 70 m / s, and stirred for 90 minutes. After fiberization, the mixture was quenched to 25°C at a rate of 15°C / min while applying pulsed shear, with one pulse cycle consisting of 10 m / s shearing for 5 seconds and 5 m / s shearing for 10 seconds. The fibrillated material was crushed and granulated to obtain a dry cathode material, which was then rolled into a film by multi-roll continuous rolling and thinned to 4 mAh / cm 2 The surface capacity is obtained to obtain a dry-process positive electrode active layer, and the dry-process positive electrode active layer is compounded with a carbon-coated aluminum foil to obtain the high-performance dry-process positive electrode sheet, and the uniformity of the binder in the dry-process positive electrode active layer is 97%.

[0057] Among them, the positive electrode active material is LiNi 0.8 Co 0.1 Mn 0.1 O2, sourced from Xiamen Tungsten Co., Ltd., model M821A. The solid electrolyte is Li6PS5Cl, sourced from Shandong Xinjieneng Lithium Battery Co., Ltd., model LPSCl. The conductive agent is Super p and VGCF with a mass ratio of 1:1. Super p is sourced from Tianjin Youmeng Chemical Technology Co., Ltd., and VGCF is sourced from Showa Denko Co., Ltd., model VGCF-H. The carbon coating layer of the carbon-coated aluminum foil is a mixture of conductive carbon black and polyacrylic acid with a mass ratio of 8:2, and the thickness of the carbon coating layer is 1μm. LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, Li6PS5Cl, Super p, VGCF and PTFE is 70:26.5:1.5:1.5:0.5.

[0058] Negative electrode: Lithium-indium alloy sheet is selected as the negative electrode.

[0059] Preparation of solid electrolyte layer: 1000 mg of Li6PS5Cl powder was placed in a mold with a diameter of 10 mm and pressurized to 100 MPa to obtain a solid electrolyte layer.

[0060] Battery Preparation: The dry-process positive electrode sheet, solid electrolyte layer, and negative electrode sheet are sequentially placed into a mold for assembly. After assembly, the pressure is applied to 100 MPa and the nuts at the top of the columns are tightened to maintain constant pressure to produce an all-solid-state lithium-ion battery. The assembly process is completed in an argon-filled glove box. The diameter of the dry-process positive electrode sheet and the lithium-indium alloy sheet are both 10 mm.

[0061] Example 2

[0062] The sieving process of the binder was adjusted to obtain a PTFE with a median particle size of 50 μm. The other steps of preparing the battery (including the preparation process of the solid electrolyte layer and the negative electrode sheet, etc.) were the same as those in Example 1.

[0063] Example 3

[0064] The sieving process of the binder was adjusted to obtain a PTFE with a median particle size of 20 μm. The other steps of preparing the battery were the same as those in Example 1.

[0065] Example 4

[0066] The content of the binder in the dry-process positive electrode active layer was adjusted to 0.2 wt %, and the proportions of the other components remained unchanged. The other steps in preparing the battery were the same as those in Example 1.

[0067] Example 5

[0068] The content of the binder in the dry-process positive electrode active layer was adjusted to 1 wt %, and the proportions of the other components remained unchanged. The other steps in preparing the battery were the same as those in Example 1.

[0069] Example 6

[0070] The mixed material was subjected to a fiberization treatment to obtain a fibrillated material. The first stage treatment temperature was 20°C, the stirring line speed was 20m / s, and the stirring time was 10min; the second stage treatment temperature was 60°C, the stirring line speed was 40m / s, and the stirring time was 10min; the third stage treatment temperature was 90°C, the stirring line speed was 60m / s, and the stirring time was 60min. After the fiberization was completed, it was quenched to 25°C at a rate of 15°C / min, and pulse shearing was applied at the same time. One pulse cycle was 10m / s shearing for 5s and 5m / s shearing for 10s. The preparation steps of the other batteries were the same as those in Example 1.

[0071] Example 7

[0072] The mixture is subjected to fibrillation to obtain a fibrillated material, the first stage processing temperature is 20℃, the stirring linear velocity is 40m / s, and the stirring duration is 10min; the second stage processing temperature is 60℃, the stirring linear velocity is 70m / s, and the stirring duration is 10min; the third stage processing temperature is 90℃, the stirring linear velocity is 50m / s, and the stirring duration is 60min. After the fibrillation is completed, it is quenched to 25℃ at a rate of 10℃ / min, while pulse shear is applied, one pulse cycle is 10m / s shear for 5s and 5m / s shear for 10s. The preparation steps of other batteries and example 1 are the same.

[0073] Example 8

[0074] The molecular weight of the binder is 8000 kg / mol, which is from Daikin Fluorinated Chemicals, and the model is F121. The preparation steps of other batteries and example 1 are the same.

[0075] Example 9

[0076] LNMO is used to replace LiNi 0.8 Co 0.1 Mn 0.1 O2, and LNMO is specifically Li2ZrO3-coated single-crystal LiNi 0.5 Mn 1.5 O4, which is from Xiamen Tungsten Co., Ltd., and the model is XW46. The preparation steps of other batteries and example 1 are the same.

[0077] Example 10

[0078] The binder is replaced with ethylene-vinyl acetate copolymer, which is from DuPont, and the model is Elvax 40W. The preparation steps of other batteries and example 1 are the same.

[0079] Comparative Example 1

[0080] The screening process of the binder is adjusted, and the PTFE median particle size obtained is 20μm. When obtaining the premix, the stirring linear velocity is 30m / s, the stirring duration is 30min, and the processing temperature is 25℃. When obtaining the mixture, the stirring linear velocity is 15m / s, the stirring duration is 30min, and the processing temperature is 10℃. The mixture is subjected to fibrillation to obtain a fibrillated material, the stirring linear velocity is 50m / s, the stirring duration is 20min, and the processing temperature is 100℃. After the fibrillation is completed, it is naturally cooled to 25℃, and no pulse shear is applied during the cooling process. The preparation steps of other batteries and example 1 are the same.

[0081] Comparative Example 2

[0082] The median particle size of PTFE is 36 μm, and its content in the dry-process positive electrode active layer is 0.5 wt %. The preparation steps of the positive electrode sheet and other batteries are the same as those in Comparative Example 1.

[0083] Comparative Example 3

[0084] The binder content in the dry-process positive electrode active layer was adjusted to 0.2 wt %, and the proportions of the other components remained unchanged. The preparation steps of the positive electrode sheet and other batteries were the same as those in Comparative Example 1.

[0085] Comparative Example 4

[0086] The binder content in the dry-process positive electrode active layer was adjusted to 1 wt %, and the proportions of the other components remained unchanged. The preparation steps of the positive electrode sheet and other batteries were the same as those in Comparative Example 1.

[0087] Comparative Example 5

[0088] The median particle size of PTFE is 400 μm, and the preparation steps of the positive electrode sheet and other batteries are the same as those in Comparative Example 1.

[0089] Comparative Example 6

[0090] The sieving process of the binder was adjusted to obtain a PTFE with a median particle size of 80 μm and a binder content of 0.3 wt % in the dry-process positive electrode active layer. The other steps in preparing the battery were the same as those in Example 1.

[0091] Comparative Example 7

[0092] The binder has a molecular weight of 2000 kg / mol and is sourced from Daikin Fluorochemical, model F104. The other steps in preparing the battery are the same as those in Example 1.

[0093] In the present invention, all unlabeled reagents and raw materials used in Examples 1-10 and Comparative Examples 1-7 are commercially available. Performance tests were performed on the dry-process positive electrode sheets and all-solid-state lithium-ion batteries in Examples 1-10 and Comparative Examples 1-7, and the test results were recorded.

[0094] In one embodiment of the present invention, to determine the uniformity of the binder in the dry-process positive electrode active layer, Fourier transform infrared spectroscopy (FTIR) can be used to confirm the specific type of binder in the electrode. For example, the binder type can be determined by directly examining the electrode surface or scraping a powder sample based on the peak positions of characteristic functional groups. After determining the binder type, the characteristic chemical bonds of the binder are selected as the target for characterization. Energy dispersive X-ray spectroscopy (EDS) is used to observe the uniformity of the binder on the surface of the dry-process positive electrode. Specifically, the uniformity of the binder distribution can be best observed by increasing the magnification to 5000x. The specific process involves first selecting the central area of ​​the electrode as the observation area. Five 50μm x 50μm areas are randomly selected, arranged along the same line with a center-to-center spacing of 500μm. The EDS surface scan is used to determine the proportions of different elements, and the characteristic element of the binder is selected as the result for this area, such as F for PTFE. Obtain the ratio of the standard deviation of the F element content in these five regions to the mean, and subtract this ratio from 1. The result obtained is used as the uniformity of the binder within the dry-process positive electrode sheet of a sample. Five dry-process positive electrode sheets obtained from the same embodiment or comparative example are selected as parallel samples, and the binder uniformity data of the five parallel samples is obtained. The average value is recorded as the binder uniformity for that embodiment or comparative example.

[0095] In one embodiment of the present invention, the binder content is obtained by testing the characteristic element absorption peak of the binder by Fourier transform infrared spectroscopy. For example, PTFE has a unique infrared absorption peak (such as 1200 cm -1 -1300cm -1 FTIR can be used to quantitatively analyze the PTFE content, specifically the C-F bond vibration peak at the center of the FTIR spectrum. Procedure: Grind the dry-process cathode active layer sample into a powder, mix the powder with KBr, and press the pellet. Alternatively, directly use ATR (attenuated total reflectance) mode to collect the sample's infrared spectrum and quantitatively analyze the PTFE content in the dry-process cathode active layer using a calibration curve or peak area integration.

[0096] In one embodiment of the present invention, the binder exists in the form of nanofibers in the dry-process positive electrode sheet, and the diameter of the nanofibers is tested by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The positive electrode sheet is placed in a test device, and at a maximum magnification of 50,000, a fiber with a length greater than 5 μm is taken, and a point value width is taken every 200 nm along the fiber axis. The average value of the width of each point value is obtained as the diameter of the fiber. 100 fibers are randomly selected and arranged from small to large in diameter to obtain the diameters at the 10th, 50th, and 90th positions, which are recorded as d10 d 50 d 90 .

[0097] Five dry-process positive electrode sheets obtained in the same embodiment or comparative example were selected as parallel samples. The d value of the nanofiber binder of each parallel sample was obtained as above. 10 d 50 and d 90 , and obtain d for 5 parallel samples 50 and d 90 / d 10 The average value is taken as the d value of this embodiment or comparative example. 50 and d 90 / d 10 Numeric value.

[0098] In one embodiment of the present invention, in order to obtain normal temperature cycle performance, the all-solid-state lithium-ion batteries obtained in Examples 1-10 and Comparative Examples 1-7 were subjected to long-cycle charge and discharge after constant capacity at 25°C, and the number of normal temperature cycle laps was measured. The test conditions are to perform a long-cycle charge and discharge test on the battery after constant capacity, and record the first-cycle discharge specific capacity during the process. When the battery capacity reaches 80% (80% State of Health, 80% SOH) of the first-cycle capacity, the test is terminated to obtain the normal temperature cycle laps. For Examples 1-8, 10, and Comparative Examples 1-7, the test voltage range is 1.9V-3.7V, and the constant capacity current is 0.6mA. The normal temperature cycle test ratio is 0.3C. For Example 9, its test method is the same as that of other embodiments and comparative examples, except that the test voltage range is 1.4V-4.25V.

[0099] Table 1. Dry-process positive electrode plate parameters and battery performance in Examples 1-7 and Comparative Examples 1-7

[0100]

[0101] As shown in Table 1, it can be seen from the comparison of Examples 1-3 that as the D50 of the binder particles decreases, the D50 of the binder nanofibers in the positive electrode sheet obtained by the preparation process provided by this application is reduced under the same content and preparation process. 50 The smaller the d 90 / d 10 The smaller the diameter of the nanofibers, the more uniform the dispersion of the binder fibers, and the uniformity of the diameter of the binder nanofibers, thereby improving the uniformity of the binder in the positive electrode sheet, improving the ion transmission capacity, and increasing the first cycle discharge capacity of the battery. However, the reduction in the diameter of the nanofibers will lead to a decrease in the cohesive force of the electrode sheet, resulting in a decrease in the cycle performance of the battery. Comparing Example 1 and Comparative Example 6, it can be seen that when the D50 of the binder particles is greater than 50nm, for example, 80nm, the d50 of the obtained binder nanofibers is greater than 50nm. 50and d 90 / d 10 The larger the particle size, the poorer the uniformity of the binder, which leads to a decrease in battery performance. Therefore, the D50 of the binder particles is controlled to make the nanofiber d 50 and uniformity are within the set range to improve the ion transmission capacity of the positive electrode sheet, thereby improving the first-cycle discharge capacity of the battery and ensuring the cycle performance.

[0102] As shown in Table 1, by comparing Example 1 and Comparative Example 2, it can be seen that when the preparation process provided by the present application is not adopted, at the same D50 and content of the binder particles, the d 50 Larger, and d 90 / d 10 The larger the diameter, and -5≤0.2X1-X2≤5 is, the larger the binder fiber diameter is, and the binder thickness uniformity is poor, resulting in a low uniformity of the binder in the dry-process positive electrode sheet, which leads to a decrease in ion transmission capacity and the first-cycle discharge capacity of the battery. In addition, the uneven distribution of nanofiber diameters will lead to a decrease in the cohesion of the electrode sheet and a decrease in the cycle performance of the battery. Moreover, when the preparation process provided by the present application is not adopted, in Comparative Example 1, further reducing the binder particle size cannot improve the uniformity of the binder in the positive electrode sheet. Therefore, when the preparation process provided by the present application is adopted, by controlling the D50 of the binder particles, the uniformity of the binder can be improved, thereby improving the performance of the obtained dry-process positive electrode sheet.

[0103] As shown in Table 1, by comparing Examples 1, 4-5, it can be seen that, through the preparation process provided by the present application, under the same conditions of D50 of the binder particles and the preparation process, as the binder content increases, the d50 of the binder nanofibers in the obtained positive electrode sheet increases. 50 Increase, d 90 / d 10 The density of the binder increases, which reduces the uniformity of the binder fiber dispersion and the uniformity of the binder nanofiber diameter. This reduces the uniformity of the binder in the dry-process positive electrode sheet, leading to a slight decrease in the battery's first-cycle discharge capacity and cycle performance. This is because as the binder content increases, the binder content in the positive electrode sheet increases, resulting in an increase in the area occupied by the binder, a decrease in the binder uniformity, and a reduction in the number of ion pathways. Therefore, controlling the binder content and thus the binder uniformity within a set range can improve the performance of the dry-process positive electrode sheet.

[0104] Please refer to Table 1. Comparing Examples 4-5 and Comparative Examples 3-4, it can be seen that when the preparation process provided by the present application is not adopted, at the same D50 and content of the binder particles, when the binder content is 0.2wt%, the positive electrode sheet cannot form a film. Therefore, through the preparation process of the present application, while improving the uniformity of the binder, it is also possible to reduce the amount of binder used, thereby improving the first-cycle discharge capacity of the battery, and making the thickness and distribution of the nanofibers uniform, thereby improving the cycle performance of the battery. At the same D50 and content of the binder particles, and when film formation is possible, when the preparation process provided by the present application is not adopted, the d50 of the binder nanofibers is 0.2wt%. 50 Larger, and d 90 / d 10 The larger it is, and -5≤0.2X1-X2≤5 is not satisfied, that is, the diameter of the obtained binder fiber is larger, and the uniformity of the binder thickness is poor, so that the uniformity of the binder in the positive electrode is low, resulting in a decrease in the ion transmission capacity and the first-cycle discharge capacity of the battery. In addition, the uneven distribution of the nanofiber diameter will lead to a decrease in the cohesion of the electrode and a decrease in the cycle performance of the battery.

[0105] Please refer to Table 1. By comparing Examples 1 and 6, it can be seen that the d 50 d 90 / d 10 And the uniformity meets the requirements of the positive electrode. When the parameters selected in the preparation process exceed the set range, the d 90 / d 10 It is 1.5, that is, the thickness of the binder nanofibers is unevenly distributed, which leads to a decrease in the uniformity of the binder. At this time, the uniformity of the binder is 95%, and the first-cycle discharge capacity and cycle performance of the battery are slightly reduced.

[0106] As shown in Table 1, by comparing Example 1 and Comparative Example 5, it can be seen that when the binder is a binder with an existing particle size, the D50 of the binder is 400 μm, and when the preparation method provided by the present application is not adopted, the diameter d of the binder nanofiber is obtained. 50 Reach 140nm, and the d of the binder nanofibers 90 / d 10 It reached 3.1, indicating that the thickness uniformity of the nanofibers of the binder is low, resulting in poor uniformity of the binder, reduced ion transmission capacity, a decrease in the first-cycle discharge capacity of the battery, and uneven dispersion of the cohesive force of the electrode, and a decrease in the cycle performance of the battery.

[0107] Table 2. Dry-process positive electrode plate parameters and battery performance in Examples 1, 8 and Comparative Example 7

[0108]

[0109] As shown in Table 2, by comparing Examples 1, 8 and Comparative Example 7, it can be seen that under the same preparation process, when the D50 and content of the binder particles are the same, only the molecular weight of the binder is changed, the binder nanofiber d 50 d 90 / d 10 As the molecular weight of the binder increases, the strength of the obtained nanofibers increases, thereby improving the performance of the positive electrode sheet and, therefore, the performance of the battery.

[0110] Table 3. Dry-process positive electrode plate parameters and battery performance in Examples 1, 9-10

[0111]

[0112] Refer to Table 3. Comparing Example 1 and Example 9, it can be seen that when different positive electrode active materials are selected, the type, particle size, content and preparation method of the binder are the same, the nanofiber d 50 d 90 / d 10 The difference in the first cycle discharge capacity of the battery is large, but the difference in cycle performance is not large. This shows that when different positive electrode active materials are selected, the first cycle discharge capacity varies due to the different positive electrode active materials, but both can improve the cycle performance of the battery. Comparing Example 1 and Example 10, it can be seen that when different binders are selected, the particle size, content and preparation method of the binder are the same, the nanofiber d 50 d 90 / d 10 The uniformity is similar, and the first-cycle discharge specific capacity and cycle performance of the battery are not much different. This shows that when selecting different binders, by controlling the particle size and content of the binder, a positive electrode sheet with higher uniformity can be obtained, thereby improving the performance of the battery.

[0113] The present invention also provides an electronic device, which includes at least one of the above-mentioned all-solid-state lithium-ion batteries, and the all-solid-state lithium-ion battery is used to provide electrical energy. The electronic device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and an electric tool. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, which may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range vehicle. The spacecraft includes airplanes, rockets, space shuttles, and spacecrafts, and the electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys. The electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers. The electronic device includes the above-mentioned all-solid-state lithium-ion battery, and therefore includes the advantages of the above-mentioned all-solid-state lithium-ion battery, which will not be elaborated on here.

[0114] In summary, the present invention proposes a dry-process positive electrode plate and its preparation method and application. By improving the uniformity of the binder in the dry-process positive electrode active layer, it can promote the effective transmission of lithium ions and electrons while ensuring the mechanical stability of the positive electrode plate, improve the performance of the positive electrode plate, reduce the risk of shedding and short circuit of the dry-process positive electrode active layer, and improve safety performance. It can control the diameter of the binder nanofibers and at the same time control the uniformity of the thickness distribution of the nanofiber diameter, which can ensure sufficient cohesion and help improve the uniformity of the binder in the dry-process positive electrode active layer. It can avoid the obstruction of ion transmission caused by local fibers being too thick, and it can also avoid the local mechanical strength being insufficient caused by local fibers being too thin, thereby improving the performance of the positive electrode plate. It can reduce the content of the binder while ensuring the uniformity of the binder, and can prepare a dry-process positive electrode plate with both good mechanical properties and efficient ion transmission, thereby improving the energy density of the battery. By regulating the parameters in the preparation of dry-process positive electrode sheets, the distribution of the components in the positive electrode sheets can be more even and the fibrillation effect can be better, thereby preparing dry-process positive electrode sheets with excellent performance, thereby improving the capacity and cycle performance of the battery.

[0115] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as the technical solutions formed by the mutual replacement of the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0116] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A dry-process positive electrode sheet, characterized in that: At least: positive electrode current collector; A dry-process positive electrode active layer is provided on at least one surface along the thickness direction of the positive electrode current collector, wherein the dry-process positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder; and the uniformity of the binder in the dry-process positive electrode active layer is greater than 95%; The binder exists in the dry-process positive electrode active layer in the form of nanofibers, and the diameter d of the nanofibers is 50 4nm-10nm, d 90 / d 10 ≤1.5, where d 50 is the diameter of the nanofibers when the number of nanofibers increases from small to large to 50%, d 10 is the diameter of the nanofibers when the number of nanofibers from small to large accumulates to 10%, d 90 The diameter of the nanofibers when the cumulative number of nanofiber diameters from small to large reaches 90%; The uniformity is achieved by: The middle area of ​​the dry-process positive electrode sheet was selected as the observation object, and 5 50μm×50μm areas were randomly selected. The 5 areas were arranged along the same line with a center interval of 500μm. The proportions of different elements were obtained by surface scanning using energy dispersive X-ray spectroscopy. The characteristic elements of the binder were selected as the results of the area. The ratio of the standard deviation and the mean of the characteristic element content of these 5 areas was obtained. The ratio was subtracted from 1 to obtain the uniformity of the binder in the dry-process positive electrode sheet.

2. The dry-process positive electrode sheet according to claim 1, characterized in that: The content of the binder in the dry-process positive electrode active layer is 0.2 wt %-1 wt %.

3. The dry-process positive electrode sheet according to claim 1, characterized in that: The binder includes one or more combinations of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-vinyl acetate copolymer, polypropylene, polyethylene, ethylene-octene copolymer or polyimide.

4. The dry-process positive electrode sheet according to claim 1, characterized in that: The positive electrode active material is selected from at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide or lithium-rich manganese-based oxide; And / or, the conductive agent is selected from at least one of graphite, graphene, carbon black, carbon fiber and carbon nanotubes.

5. A method for preparing a dry-process positive electrode sheet, for preparing the dry-process positive electrode sheet according to any one of claims 1 to 4, characterized in that: At least the following steps are included: Sieving binder particles with a preset median particle size; Mixing the positive electrode active material, the conductive agent, and the binder particles to obtain a mixed material; performing a fibrillation treatment on the mixed material to obtain a fibrillated material; Cooling the fibrillated material to a target temperature at a preset rate while applying shear to obtain an intermediate product; Crushing and granulating the intermediate product to obtain a dry-process positive electrode material; The dry-process positive electrode material is formed into a film by continuous rolling with multiple rollers to obtain a dry-process positive electrode active layer; The dry-process positive electrode active layer is compounded with the positive electrode current collector to obtain a dry-process positive electrode sheet.

6. The method for preparing a dry-process positive electrode sheet according to claim 5, characterized in that: The preset median particle size of the binder particles is X1 μm, and the diameter d of the nanofibers in the dry-process positive electrode active layer is 50 If it is X2 nm, then the relationship is: -5≤0.2X1-X2≤5; And / or, the binder particles have a preset median particle size of 20 μm to 50 μm.

7. The method for preparing a dry-process positive electrode sheet according to claim 5, characterized in that: Sieving the binder particles at a preset temperature, wherein the preset temperature is 5° C.-20° C.; The fibrillation includes a first stage, a second stage and a third stage. In the first stage, the treatment temperature is 20°C-40°C, the stirring linear speed is 20m / s-30m / s, and the stirring time is 10min-30min; in the second stage, the treatment temperature is 60°C-80°C, the stirring linear speed is 40m / s-60m / s, and the stirring time is 10min-30min; in the third stage, the treatment temperature is 90°C-120°C, the stirring linear speed is 60m / s-70m / s, and the stirring time is 60min-120min; The preset rate is 10°C / min-15°C / min, and the target temperature is 25°C-40°C; During the cooling process, pulse shearing is applied, wherein one pulse shearing comprises shearing at 8 m / s-10 m / s for 4 s-6 s and shearing at 3 m / s-5 m / s for 8 s-12 s.

8. An all-solid-state lithium-ion battery, characterized in that: At least: A positive electrode sheet, selected from the dry-process positive electrode sheet according to any one of claims 1 to 4, or a dry-process positive electrode sheet obtained by the preparation method according to any one of claims 5 to 7; negative electrode; The solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet.

9. The all-solid-state lithium-ion battery according to claim 8, characterized in that: The positive electrode plate further includes a solid electrolyte, which is selected from at least one of an oxide solid electrolyte, a sulfide solid electrolyte, and a halide solid electrolyte.

10. An electronic device, characterized in that: An all-solid-state lithium-ion battery comprising the all-solid-state lithium-ion battery according to any one of claims 8 to 9.

Images